Richardson began his live-action acting career in New York City, where he performed in commercials. His first professional acting job was in an
AT&T commercial. He was frequently hired as a voice for television commercials. He later moved to
Los Angeles. He has usually portrayed villainous characters due to his deep and powerful voice. In 1995, he obtained his first voice role as Mayor Tilton on the animated television version of
The Mask. Additionally, early in his career, he appeared in a
PBS special directed by
John Houseman. Richardson's other credits include
Captain Gantu in
Lilo & Stitch and its
franchise, Shnitzel in the
Chowder pilot (and was later replaced by
John DiMaggio),
Goro in
Mortal Kombat, the second voice of Skulker on
Danny Phantom,
Sarevok in the ''
Baldur's Gate series, Jolee Bindo in Star Wars: Knights of the Old Republic, Crunch Bandicoot in the Crash Bandicoot games, Sai Sahan in Elder Scrolls Online MMORPG series, Tartarus from Halo 2, Chairman Drek in Ratchet & Clank, Antauri in Super Robot Monkey Team Hyperforce Go!, Openly Gator from Queer Duck, Doctor Payne and others on The Proud Family, Dark Laser on The Fairly OddParents, Maurice from The Penguins of Madagascar (replacing Cedric the Entertainer), Slam Tasmanian and Tech E. Coyote on Loonatics Unleashed, and the voice of Exile in the 1990s animated series Road Rovers''. Richardson replaced
Keith David as the voice of
Tombstone on
The Spectacular Spider-Man. He provided a character voice set for
Icewind Dale:
Heart of Winter and
Icewind Dale II. He was the voice of Heihachi in the PlayStation 2 game
Soul Calibur II, though he is listed in the role as Victor Stone. He also voiced Stump Smash and Tree Rex in
Skylanders: Swap Force,
Skylanders: Trap Team, and
Skylanders: SuperChargers. In 2001, Richardson voiced
Barney Rubble in the animated movie
The Flintstones: On the Rocks. In 2004, he became the first Black actor to portray the
Joker, voicing the character on the animated series
The Batman, a role for which he was twice nominated for the
Daytime Emmy Award for Outstanding Performer in an Animated Program. In 2005, he voiced
Trigon on the animated series
Teen Titans, taking over the role from
Keith Szarabajka. In 2006, he appeared in the comedy
Clerks II in which he plays a cop who notices the words "Porch Monkey 4 Life" written on the back of
Randal Graves' work jacket; he also voiced the elder dragon Terrador from
The Legend of Spyro game series. In 2008, he performed the voice of
Bishop for
Wolverine and the X-Men. Later, he did the voice of
Nick Fury on
The Super Hero Squad Show. He also voiced Tyro in
Nickelodeon's
Avatar: The Last Airbender in 2004. Richardson often plays characters based on comedian
Bill Cosby, such as on
Family Guy ("Brian Does Hollywood"); as Cosby himself on
The Boondocks; and Numbuh 5's father Mr. Lincoln, an homage to Cosby on
Codename: Kids Next Door. His most frequent role on
Family Guy is Jerome, Lois's ex-boyfriend. He was also the voice of
Cleveland Brown Jr.,
Lester Krinklesac, and numerous others on
The Cleveland Show. He currently voices Principal Brian Lewis on
American Dad! and is the current voice for
Dr. Hibbert replacing
Harry Shearer on
The Simpsons. His voice roles in 2011 included
Panthro in the
Thundercats series,
Martian Manhunter on
Young Justice and Bulkhead, one of the Autobots in
Transformers: Prime. He played
Kilowog in
Green Lantern: Rise of the Manhunters, the video game sequel to the live-action film
Green Lantern and later reprised the role in
Green Lantern: The Animated Series and
Young Justice. He was nominated for Voice Actor of the Year by Behind the Voice Actors in 2012 and in 2013. In September 2013, he provided the voice of Mr. Gus on the
Cartoon Network show
Uncle Grandpa. In 2015, he did the voice of a
Nigerian king on
The Simpsons episode "
The Princess Guide". Later, he provided the voice of Judge Michaels in
Tyler Perry's first animated film, ''
Madea's Tough Love. In 2021, he provided the voice of Jimbo in The Boss Baby: Back in Business (2018), the sequel to the 2017 film The Boss Baby''. In
2019, he was nominated for a Primetime Emmy for Outstanding Character Voice-Over Performance for
F Is For Family. ==Personal life==