Cast & Crew

Series Directed by

David Hartman
(20 episodes, 1998-2000)
Sam Liu
(7 episodes, 1998-2001)
Frank Squillace
(3 episodes, 1998-2000)
Audu Paden
(2 episodes, 1998)
Nathan Chew
(2 episodes, 1999-2001)
Alan Caldwell
(2 episodes, 1999-2000)
Brad Rader
(2 episodes, 2000)
Christopher Berkeley
(1 episode, 1999)
Sean Song
(1 episode, 2000)

Series Writing Credits

Jeff Kline
(developer) (39 episodes, 1998-2001)
Jeff Kline
(developed by) (1 episode, 1998)
Richard Raynis
(developer) (39 episodes, 1998-2001)
Richard Raynis
(developed by) (1 episode, 1998)
Marty Isenberg
(written by) (3 episodes, 1998-2001)
Steven Melching
(written by) (3 episodes, 1998-1999)
Robert N. Skir
(written by) (2 episodes, 1998)
Steve Perry
(writer) (1 episode, 1998)
Neil Ruttenberg
(written by) (1 episode, 1998)
Len Wein
(written by) (1 episode, 1998)
Marv Wolfman
(written by) (1 episode, 1998)
Baz Hawkins
(writer) (1 episode, 1999)
Steve Hayes
(1 episode, 1999)
Steve L. Hayes
(1 episode, 1999)
Harry 'Doc' Kloor
(written by) (1 episode, 1999)
Scott Lobdell
(written by) (1 episode, 1999)
Gregory K. Pincus
(written by) (1 episode, 1999)
Brooks Wachtel
(writer) (1 episode, 1999)
Steve Cuden
(written by) (1 episode, 2000)
Carl Ellsworth
(written by) (1 episode, 2000)
Janna King
(writer) (1 episode, 2000)
William Stout
(writer) (1 episode, 2000)
Jeffrey Wynne
(written by) (1 episode, 2000)
Angel Dean Lopez
(written by) (1 episode, 2001)
Craig Miller
(writer) (unknown episodes)

Series Cast

Ian Ziering
 Dr. Nick Tatopoulos 40 episodes, 1998-2001
Malcolm Danare
 Dr. Mendel Craven 40 episodes, 1998-2001
Rino Romano
 Randy Hernandez / ... 40 episodes, 1998-2001
Charity James
 Dr. Elsie Chapman 40 episodes, 1998-2001
Brigitte Bako
 Monique DuPre 39 episodes, 1998-2001
Tom Kenny
 N.I.G.E.L. / ... 28 episodes, 1998-2001
Kevin Dunn
 Major Anthony Hicks 20 episodes, 1998-2000
Paget Brewster
 Audrey Timmonds 11 episodes, 1998-2001
Joe Pantoliano
 Victor 'Animal' Palotti 8 episodes, 1998-2001
Scott Mosenson
 Dr. Hans Sopler 3 episodes, 1999
Patrick Labyorteaux
 Dr. Ted Hoffman 3 episodes, 1999
David Newsom
 Cameron Winter 3 episodes, 1998-2000
Bob Joles
 Hank / ... 3 episodes, 1998-2000
Michael Lerner
 Mayor Ebert 3 episodes, 1998-1999
Keith Szarabajka
 Philippe Roaché 2 episodes, 1999
Nicholas Guest
 Chad Gordon / ... 2 episodes, 1999-2000
Clancy Brown
 Announcer / ... 2 episodes, 1999
Ronny Cox
 Dale 2 episodes, 1998-2000
Maggie Macmillan
 Susan Saunders 1 episode, 1999
Edward Albert
 Captain Briggs 1 episode, 2000
Max Brooks
 Lawyer 1 episode, 2000
Gino Conforti
 Frank Whitaker 1 episode, 2000
Susan Eisenberg
 Dr. Candace Kirk 1 episode, 2000
Mikey Kelley
 Steven 1 episode, 2000
Bobby Holliday
 Scientist 1 episode, 2000
Tate Donovan
 Lawrence Cohen 1 episode, 1998
Tony Plana
 General Albondiga 1 episode, 1998
Estelle Harris
 Old Lady / ... 1 episode, 1998
Bumper Robinson
 Looter #2 1 episode, 1998
Charles Howerton
 Dr. Ted Hoffman 1 episode, 1998
Roddy McDowall
 Dr. Hugh Trevor 1 episode, 1999
Clyde Kusatsu
 Japanese Border Patrol Agent 1 episode, 1999
Dorian Harewood
 Bounty Man / ... 1 episode, 1999
Pete Sepenuk
 Train Conductor 1 episode, 1999
Michael Chiklis
 Colonel Charles Tarrington 1 episode, 2000
Kevin Michael Richardson
 Queens Transit Authority / ... 1 episode, 2000
Robbie Rist
 Kevin 1 episode, 2000
Dan Gilvezan
 TV Reporter 1 episode, 2000
John Mooney
 Stan 1 episode, 2000
Kenneth Mars
 Dr. Alexander Preloran 1 episode, 1998
Steve Susskind
 Sidney Walker 1 episode, 1998
Clive Revill
 Eustace McPhail 1 episode, 1999
Nick Jameson
 Dr. Jonathan Insley 1 episode, 1999
Page Leong
 Dr. Yukiko Ifukube / ... 1 episode, 1999
Steve Staley
 Additional Voices 1 episode, 1999
Steve Vinovich
 Ted 1 episode, 1999
Mae Whitman
 Meg 1 episode, 2000
Robert Forster
 Jack Chapman / ... 1 episode, 2000
Peter Strauss
 Ray Valdes 1 episode, 2000
Joseph Gian
 Co-Pilot 1 episode, 2000
Michael Reisz
 Trespasser #1 1 episode, 2000
Roger Scott
 News Reporter 1 episode, 2000
Jesse Corti
 Paul Dimanche 1 episode, 2001
Ron Perlman
 Leviathan Alien / ... 1 episode, 1998
David Paymer
 Dean Whitehead 1 episode, 1998
Victor Brandt
 Hobo 1 episode, 1998
Pamela Adlon
 Animal's Son / ... 1 episode, 1999
Mark Rolston
 Captain Moore 1 episode, 1999
James Horan
 Professor Kasam 1 episode, 1999
Tony Masa
 Hiker #1 1 episode, 1999
Doug Savant
 Trespasser #2 1 episode, 2000
Alice Hirson
 Peg Chapman 1 episode, 2000
Melissa Disney
 Waitress 1 episode, 2000
Stuart Pankin
 Milo Sanders 1 episode, 2001
Susan Blu
 Doctor #2 1 episode, 1998
Grant Shaud
 Dr. Felix Hoenikker 1 episode, 1998
Linda Blair
 Alexandra Springer 1 episode, 1999
Dennis Haysbert
 General Ekwensi 1 episode, 1999
Andy Milder
 Archaeologist 1 episode, 1999
Morri Chowaiki
 Lieutenant 1 episode, 1999
Mimi Ketelsen
 Rich Woman 1 episode, 1999
Karen Kolton
 Kate Chapman 1 episode, 2000
Peter Renaday
 Georges 1 episode, 2001
John Rubinow
 TV Reporter 1 episode, 2001

Series Produced by

Dean Devlin
executive producer (40 episodes, 1998-2001)
Roland Emmerich
executive producer (40 episodes, 1998-2001)
Jeff Kline
co-executive producer (40 episodes, 1998-2001)
Audu Paden
producer (40 episodes, 1998-2001)
Richard Raynis
executive producer (40 episodes, 1998-2001)
Ping Warner
coordinating producer (40 episodes, 1998-2001)
Kimberly Smith
associate producer (38 episodes, 1998-2001)
Joel Kuwahara
consulting animation co-producer (6 episodes, 1998)
Sarah Finn
associate producer (2 episodes, 1998)

Series Music by

Jim Latham
(31 episodes, 1998-2001)

Series Editing by

C.K. Horness
(28 episodes, 1999-2001)
Adam Weiss
(27 episodes, 1999-2001)
Richard C. Allen
(10 episodes, 1998-1999)

Series Production Management

Tonda S. Lark
post-production supervisor: studio (39 episodes, 1998-2001)
Nathania Seales
post-production supervisor (38 episodes, 1998-2001)
Armando Plata
production supervisor (33 episodes, 1998-2001)
Chuck Smith
post-production supervisor (29 episodes, 1999-2001)
Brian Marshall
production supervisor (26 episodes, 1999-2001)
J.C. Cheng
production supervisor (10 episodes, 1998-1999)
Jason Hindman
post-production supervisor (2 episodes, 1998)
Kimberly A. Smith
production supervisor (2 episodes, 1998)
David Singer
production supervisor (2 episodes, 1999)
Jun Ho Hwang
production manager: overseas (1 episode, 1998)

Series Second Unit Director or Assistant Director

Tim Eldred
assistant director (40 episodes, 1998-2001)
Toshiyuki Hiruma
assistant director (40 episodes, 1998-2001)
Audu Paden
assistant director (40 episodes, 1998-2001)

Series Art Department

Kevin Hanley
color director (40 episodes, 1998-2001)
Jay Hong
prop design (40 episodes, 1998-2001)
Ray Leung
prop design (40 episodes, 1998-2001)
Dirk Okumoto
prop design (40 episodes, 1998-2001)
Eugene Mattos
prop supervisor (37 episodes, 1998-2001)
Kathleen Hartman
prop design / prop designer (30 episodes, 1999-2001)
David Hartman
storyboard artist / storyboard clean-up artist (29 episodes, 1998-2001)
Tom Ryder
storyboard clean-up artist / storyboard artist (25 episodes, 1998-2001)
James Donvito
prop design (24 episodes, 1999-2001)
David Manners
storyboard clean-up artist (23 episodes, 1998-2000)
Norm Ryang
prop design / prop designer (23 episodes, 1999-2001)
Seung Eun Kim
storyboard clean-up artist / storyboard artist (20 episodes, 1998-2000)
Samuel Montes
storyboard clean-up artist / storyboard artist (19 episodes, 1998-2001)
Sebastian Montes
storyboard clean-up artist / storyboard artist (18 episodes, 1998-2000)
Byron Penaranda
storyboard clean-up artist (17 episodes, 1998-2001)
Tim Divar
storyboard artist / storyboard clean-up artist (16 episodes, 1998-2001)
Michael Docherty
storyboard clean-up artist / storyboard artist (16 episodes, 1998-2000)
Will Sweeney
storyboard clean-up artist / storyboard artist (13 episodes, 1998-2000)
Carlos Lemos
storyboard clean-up artist (13 episodes, 1999-2000)
Jay Oliva
storyboard artist (12 episodes, 1998-2001)
Tenny Henson
storyboard clean-up artist / storyboard artist (12 episodes, 1998-2000)
Vincent Edwards
storyboard artist (10 episodes, 1998-2000)
Kathleen Poirer
prop design (10 episodes, 1998)
Keith Aiken
storyboard clean-up artist (10 episodes, 1999-2000)
Armando Gil
storyboard clean-up artist / storyboard artist (10 episodes, 1999-2000)
Don Hudson
storyboard clean-up artist (9 episodes, 1998)
Anthony Chun
storyboard clean-up artist (9 episodes, 1999-2001)
Brandon Kruse
storyboard clean-up artist (9 episodes, 1999-2001)
James Yang
storyboard clean-up artist (8 episodes, 1999-2001)
Pat Agnasin
storyboard clean-up artist / storyboard artist (7 episodes, 1999-2000)
Michael Chang
storyboard artist / storyboard clean-up artist (7 episodes, 1999-2000)
Romeo Francisco
storyboard artist / storyboard clean-up artist (7 episodes, 1999-2000)
Min Kim
storyboard artist (7 episodes, 1999-2000)
Ric Estrada
storyboard artist / storyboard clean-up artist (6 episodes, 1999-2001)
Andres Alvarez
storyboard revisionist (6 episodes, 1999)
Fil Barlow
creature and character designer (5 episodes, 1998)
Sean Song
storyboard artist (5 episodes, 1999-2000)
Charles Kocel
art coordinator (4 episodes, 1998)
Brian Marshall
art coordinator (4 episodes, 1999)
Chap Yaep
storyboard artist / storyboard clean-up artist (4 episodes, 2000-2001)
Christopher Berkeley
storyboard artist (3 episodes, 1998)
Alan Caldwell
storyboard artist (3 episodes, 1998)
Michael Macasero
art coordinator (3 episodes, 1998)
Jane Wu
storyboard artist (3 episodes, 1999-2001)
Jeff Allen
storyboard clean-up artist / storyboard artist (3 episodes, 1999-2000)
Mike Borkowski
storyboard clean-up artist / storyboard artist (3 episodes, 1999-2000)
Ron Roesch
prop design (3 episodes, 1999-2000)
Vinton Heuck
storyboard clean-up artist (3 episodes, 1999)
Alex Summers
storyboard artist (3 episodes, 1999)
Sam Liu
storyboard artist (2 episodes, 1998-2001)
Armando Carrillo
storyboard artist (2 episodes, 1998-1999)
Tim Eldred
storyboard artist (2 episodes, 1998)
Rick Hoberg
storyboard artist (2 episodes, 1999-2001)
Glen Hill
storyboard artist (2 episodes, 1999)
Kyle Menke
storyboard artist (2 episodes, 2000-2001)
Brandon Vietti
storyboard artist (2 episodes, 2000)
Mike Vosburg
storyboard artist (2 episodes, 2000)
John Diaz
art coordinator (1 episode, 1998)
Jim Manocchio
background designer (1 episode, 1998)
Frank Squillace
storyboard artist (1 episode, 1998)
Armando Plata
art coordinator (1 episode, 1999)
David Chlystek
storyboard artist (1 episode, 2000)
Declan Moran
storyboard artist (1 episode, 2000)
Rafael Rosado
storyboard artist (1 episode, 2000)

Series Sound Department

Michael Beiriger
re-recording mixer (40 episodes, 1998-2001)
Devon Bowman
assistant engineer (40 episodes, 1998-2001)
Kris Daly
foley recordist (40 episodes, 1998-2001)
Phyllis Ginter
foley artist (40 episodes, 1998-2001)
Ray Leonard
re-recording mixer (40 episodes, 1998-2001)
Tom Mgrdichian
recording engineer (40 episodes, 1998-2001)
Robbi Smith
dialogue editor (40 episodes, 1998-2001)
Robert Duran
sound effects editor (29 episodes, 1998-2001)
Paca Thomas
sound effects editor (11 episodes, 1998-1999)

Series Visual Effects by

Roger Injarusorn
digital effects supervisor (40 episodes, 1998-2001)
Patrick Tatopoulos
visual design consultant (39 episodes, 1998-2001)
Andy Jolliff
digital compositor: opening titles / technical director: opening titles (unknown episodes)
Kathleen Hartman
effects designer (uncredited) (25 episodes, 1998-2000)

Series Camera and Electrical Department

Myeongsoo Song
camera: overseas / overseas camera (1 episode, 1998)

Series Animation Department

Enzo Baldi
background designer (40 episodes, 1998-2001)
Traci Balthazor
color design supervisor: main title / color coordinator / color design supervisor (40 episodes, 1998-2001)
J.P. Bondy
color stylist (40 episodes, 1998-2001)
Jevon Bue
background designer (40 episodes, 1998-2001)
Eug Young Chang
animator: main title (40 episodes, 1998-2001)
Caroline Choat
character designer (40 episodes, 1998-2001)
Djinni Christener
color stylist (40 episodes, 1998-2001)
Mike Guerena
color stylist (40 episodes, 1998-2001)
Tricia Hale
background painter / color stylist (40 episodes, 1998-2001)
Jamie H. Huang
timing director (40 episodes, 1998-2001)
Chuck Jones
character designer (40 episodes, 1998-2001)
Seung Eun Kim
animator: main title (40 episodes, 1998-2001)
Michel Lyman
timing director: main title / supervising timing director (40 episodes, 1998-2001)
Helen Maier
character designer (40 episodes, 1998-2001)
Nollan Obena
background designer (40 episodes, 1998-2001)
Myra Owyang
animatic production coordinator (40 episodes, 1998-2001)
Gloria Palter
animation checker / checker (40 episodes, 1998-2001)
Thomas Perkins
character designer / character supervisor (40 episodes, 1998-2001)
Richard Raynis
director: main title (40 episodes, 1998-2001)
Kris Sherwood
supervising timing director / timing director (40 episodes, 1998-2001)
Chu-Hui Song
color stylist (40 episodes, 1998-2001)
Vince Toyama
background supervisor (40 episodes, 1998-2001)
Young Ki Yoon
animator: main title (40 episodes, 1998-2001)
Maurice Edwards
background designer (39 episodes, 1998-2001)
Mike Yang
animatic storyboard (34 episodes, 1998-2001)
Kim Truong
timing director (33 episodes, 1998-2001)
Cory Lewis
animatics assistant (30 episodes, 1998-2001)
Carmen Cano
animatic storyboard (28 episodes, 1999-2001)
Joshua Eklund
animatics assistant (28 episodes, 1999-2001)
Rex Faraday
animation checker (28 episodes, 1999-2001)
Magda Greene
animatic storyboard (28 episodes, 1999-2001)
Lori Matthews
animation checker (28 episodes, 1999-2001)
Eric Canete
background designer (25 episodes, 1999-2001)
Cindy Carrington
color stylist (25 episodes, 1999-2001)
Andy Chung
background designer (25 episodes, 1999-2001)
Ricardo Hernandez
color stylist (25 episodes, 1999-2001)
Tim Long
timing director (25 episodes, 1999-2001)
Kersti Myrberg
color stylist (25 episodes, 1999-2001)
Azariah Owens
color stylist (25 episodes, 1999-2001)
José López
character designer (24 episodes, 1999-2001)
Kunio Shimamura
timing director (23 episodes, 1998-2001)
Art Morales
background designer / background artist (23 episodes, 1999-2001)
Jonard Soriano
background designer (23 episodes, 1999-2001)
Jane Wu
storyboard artist (21 episodes, 1998-1999)
Zeon Davush
timing director (20 episodes, 1999-2001)
Bridget Bo-Lane
inbetween artist (19 episodes, 1998-1999)
Chris Haynie
color designer (19 episodes, 1999-2001)
Rachel Stratton
color stylist (18 episodes, 1998-1999)
Jeff Wong
background designer (18 episodes, 1999-2001)
Jon Suzuki
character designer (17 episodes, 1999-2001)
Edgar Carlos
background designer (16 episodes, 1999-2001)
Craig Cuqro
animatics assistant / color stylist (15 episodes, 1998-2000)
Jojo Aguilar
background designer (14 episodes, 1998-1999)
Sandi Hathcock
animation checker (12 episodes, 1998-2001)
Fred Crippen
timing director (12 episodes, 1999-2001)
Kitty Schoentag
animation checker (10 episodes, 1999-2001)
Philip A. Reynolds
timing director (9 episodes, 1999-2001)
Frank Squillace
director (8 episodes, 1998-2000)
Daniel Chiu
color stylist (8 episodes, 1999-2001)
Kristen Keeves
animatic storyboard (8 episodes, 1999-2001)
Bob Nesler
timing director (8 episodes, 1999-2001)
Jill Jacobs
timing director (6 episodes, 1998-2000)
Wayne Cash
character designer (6 episodes, 1998)
Mark Jetmir
checker (6 episodes, 1998)
Evan Mack
color stylist (5 episodes, 1998)
Mike Harris
character designer (5 episodes, 1999-2001)
Matthew Thompson
character designer (5 episodes, 1999-2000)
Aaron Crippen
timing director (4 episodes, 1999-2001)
Tony Love
timing director (4 episodes, 1999-2000)
Tom Cook
timing director (3 episodes, 1998-2000)
Tom Ray
timing director (2 episodes, 1998-1999)
Maria Rodriguez
animation checker / timing director (2 episodes, 1998-1999)
Holly du Rivage
timing director (2 episodes, 1998)
Richard Gasparian
timing director (2 episodes, 1998)
Kevin Hanley
color design supervisor (2 episodes, 1998)
Randy Ludensky
timing director (2 episodes, 1998)
Richard Trueblood
timing director (2 episodes, 1998)
Peter Aries
animation checker (1 episode, 1998)
Fil Barlow
character designer (1 episode, 1998)
Yong Duk Kim
overseas director (1 episode, 1998)
Toshiyuki Hiruma
overseas animation director (1 episode, 1998)
Ho Joon Lee
key animator: overseas (1 episode, 1998)
Yung Kyu Lee
layout artist: overseas (1 episode, 1998)
So Ji Lee
layout artist: overseas (1 episode, 1998)
Young-Il Park
background artist: overseas (1 episode, 1998)
Everett Peck
character designer (1 episode, 1998)
Yong-um Sang
layout artist: overseas (1 episode, 1998)
Kee Suk Lee
final checker: overseas (1 episode, 1998)
Sang Yeob Han
key animator: overseas (1 episode, 1998)
Becky Bristow
timing director (1 episode, 1999)
Tim Callahan
background designer (1 episode, 1999)
Ron Myrick
timing director (1 episode, 1999)
Michael Tracy
background designer (1 episode, 2000)

Series Casting Department

Christopher Meola
casting supervisor (39 episodes, 1998-2001)
Everett A. Oliver
casting coordinator (30 episodes, 1998-2000)

Series Editorial Department

Monica Lee
assistant animatic editor (40 episodes, 1998-2001)
Amie Lim
animatic editor (40 episodes, 1998-2001)
Kent Pritchett
colorist (40 episodes, 1998-2001)
Sandra Shibuya
animatic editor (40 episodes, 1998-2001)
Kirstie Cano
animatic editor (39 episodes, 1998-2001)
Michelle Johnson
post-production coordinator (39 episodes, 1998-2001)
Jhoanne Reyes
assistant editor (38 episodes, 1998-2001)
Margaret Hou
assistant editor (32 episodes, 1998-2001)
Bruce A. King
assistant editor (30 episodes, 1999-2001)
Jan Hirota
post-production coordinator (27 episodes, 1999-2001)
Ann Hoyt
assistant editor (22 episodes, 1999-2001)
Linda Nagata
post-production assistant (21 episodes, 1999-2001)
Ben Choo
assistant animatic editor (20 episodes, 1998-2000)
Dick Grunert
post-production assistant (13 episodes, 1998-1999)
Ted Supa
assistant editor (12 episodes, 1998-2000)
Robert Brousseau
post-production director (11 episodes, 1999-2001)
Gayle M. Grech
assistant editor (8 episodes, 1998)
Daniel Keller
animatic editor (4 episodes, 1999-2001)
Brett Johnson
animatic editor (2 episodes, 2000)
Traci Balthazor
color coordinator (1 episode, 1998)
Pete Hentrich
on-line editor (unknown episodes)

Series Music Department

Jim Latham
composer: theme music (40 episodes, 1998-2001)
Brian Garland
composer: additional music (unknown episodes)
Craig Sharmat
composer: additional music (unknown episodes)

Series Script and Continuity Department

Randy Jandt
script coordinator (40 episodes, 1998-2001)

Series Additional Crew

Susan Blu
dialogue director (40 episodes, 1998-2001)
Kirstin Hartenbower
assistant: Mr. Kline / assistant: mr. kline / Assistant to Mr. Kline / assistant to mr. kline (40 episodes, 1998-2001)
Bob Higgins
production executive (40 episodes, 1998-2001)
Robby Huckell
assistant: Mr. Raynis / assistant: mr. raynis / Assistant to Mr. Raynis / assistant to mr. raynis (40 episodes, 1998-2001)
Jeff Kline
developed by (40 episodes, 1998-2001)
John Diaz
production assistant / production assistant: props (38 episodes, 1998-2001)
John Diaz
production assistant (38 episodes, 1998-2001)
Michael Macasero
production assistant / production assistant: characters / production assistant: props (37 episodes, 1998-2001)
Everett Peck
executive design consultant / executive creative consultant (37 episodes, 1998-2001)
Ho Kuk
production assistant / production assistant: backgrounds (24 episodes, 1999-2001)
Marty Isenberg
story editor (22 episodes, 1998-2001)
Robert N. Skir
story editor (22 episodes, 1998-2001)
Dan Smith
recruiter (20 episodes, 1998-1999)
Jerome White
production assistant / production assistant: storyboards / production assistant: storyboard (18 episodes, 1999-2001)
Bridget Bo-Lane
production assistant: backgrounds / production assistant / production assistant: characters (9 episodes, 1998-1999)
Amanda Martin
production assistant / production assistant: backgrounds (8 episodes, 1998)
Greg Klein
story editor (7 episodes, 1999-2001)
Tom Pugsley
story editor (7 episodes, 1999-2001)
Bob Hathcock
supervising director: post-production (6 episodes, 1999-2000)
Devon Bowman
assistant engineer (1 episode, 1998)
Craig Cuqro
animatic assistant (1 episode, 1998)
Marsha F. Griffin
story editor (1 episode, 2000)

Series Thanks

Min Kim
in loving memory of (1 episode, 1999)
All Filters