His 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, 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, Slam Tasmanian and Tech E. Coyote on Loonatics Unleashed and the voice of Exile in the 1990s animated series Road Rovers. Richardson also 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.
Richardson has usually portrayed villainous characters due to his deep and powerful voice. In 1995, he obtained his first voice role; Mayor Tilton on the animated TV version of The Mask.
In 2001, he voiced Barney Rubble in the animated movie The Flintstones: On the Rocks. In 2003, he voiced Trigon in the animated series Teen Titans. Trigon is a demonic overlord and the father of Raven. In 2004, he became the first African-American to voice the Joker in the Kids WB animated series, The Batman, a role for which he was twice nominated for the Daytime Emmy Award for Outstanding Performer in a Children's Series. 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. In 2008, he did the voice of Bishop for Wolverine and the X-Men. Later, he did the voice of Nick Fury on The Super Hero Squad Show.
Richardson married his wife in May 2006 and they have two children.
Richardson's voice roles (in 2011) include Panthro in the 2011 Thundercats series, Martian Manhunter on Young Justice, and Bulkhead, one of the Autobots in Transformers: Prime.
Richardson was nominated for Voice Actor of the Year by Behind the Voice Actors in 2012 and in 2013.
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