Frank Welker's best known role is that of Fred Jones in Scooby-Doo. He has also voiced the titular character, Scooby-Doo, since 2002. Some of his other roles include:
- Superfriends (Retitled The Super Powers Team: Galactic Guardians in the final seasons) - Marvin, Wonder Dog, Mr. Mxyzptlk, Toyman, Darkseid, Kalibak and Joker (1973-1985)
- First two seasons included Norman Alden as the voice of Aquaman, as well as guest stars Plastic Man and Green Arrow.
- Spider-Man and His Amazing Friends - Bobby Drake/Iceman, Flash Thompson, Matt Murdock, Ben Parker and other characters (1981-1983)
- X-Men: Pryde of the X-Men - Toad and Lockheed the Dragon
- Included Neil Ross as Nightcrawler
- The Simpsons - Santa's Little Helper and Snowball II
- Other series regular includes Dan Castellaneta as Homer Simpson, Krusty the Clown and other characters on the series.
- Megatron - Various incarnations of The Transformers starting with the 1984 cartoon.
- Inspector Gadget - Dr. Claw (1983-1985)
- Star Trek III: The Search for Spock - Screams of Spock (1984)
- Christopher Lloyd starred as the film's antagonist Klingon Commander Krudge.
- The Real Ghostbusters - Ray Stantz and Slimer (1986-1991)
- Ducktales the Movie: Treasure of the Lost Lamp - Additional voices (1990)
- Christopher Lloyd provided the voice of the villainous sorcerer, Merlock.
- Bill & Ted's Bogus Journey - Voices of Satan, Easter Bunny and Station
- Teenage Mutant Ninja Turtles II: The Secret of the Ooze - Tokka and Rahzar (1991)
- Abu in the film Aladdin (1994-1995), The Return of Jafar (1994), Aladdin & The King of Thieves (1996) and Aladdin: The Series (1994-1995)
- Dan Castellaneta was also present in both The Return of Jafar and The Series as The Genie
- Extreme Ghostbusters - Ray Stantz in the two part episodes "Back in the Saddle" (1997).
- Several cartoons presented by Steven Spielberg, including:
- Animaniacs - Ralph the Guard, Thaddeus Plotz and Buttons (1993-1998)
In 2015, he provided voices for several characters from the Scooby Doo and Ghostbusters franchises in the video game, LEGO Dimensions, which also starred Michael J. Fox and Christopher Lloyd reprising their roles of Marty McFly and Emmett Brown.