- Maurice LaMarche
- Inspector Gadget / Chief Quimby (and in segments "The Capeman Cometh", and "Gadget's Gadgets") (voice)
- Frank Welker
- Dr. Claw / Brain / M.A.D Cat / Dr. Noodleman (segment "Gadget's Gadgets") / M.A.D Agent (segment "The Capeman Cometh") (voice)
- Cree Summer
- Penny
- Holly Berger
- Penny (segment "Gadget's Gadgets" and "The Capeman Cometh")
- Townsend Coleman
- Cpl. Capeman (segments "The Capeman Cometh" and "Gadget's Gadgets")
- Don Adams
- Inspector Gadget (segments "The Capeman Cometh" / "Prince of the Gypsies" / "Gadget's Gadgets") (voice)
- Melleny Melody
- Vespella (segment "Prince of the Gypsies")
- Greg Duffell
- M.A.D Agent (segment "Prince of the Gypsies")
- Andy Goldberg
- M.A.D Ninja (segment "The Capeman Cometh")
- Louis Nye
- M.A.D Agents (segments "The Capeman Cometh" & "Gadget's Gadgets")
- Rita Taggart
- M.A.D Nurse (segment "Gadget's Gadgets")
- Don Francks
- King (segment "Prince of the Gypsies")
- Dan Hennessey
- Chief Quimby (segment "Prince of the Gypsies")
