Williams has appeared in films such as Undercover Brother, appearing as Smart Brother (having previously voiced the Undercover Brother character in the original internet animated series), Harold & Kumar Go to White Castle, and Soul Plane. On the Boondocks second-season premiere, ". . . Or Die Trying", Riley Freeman and Robert Freeman are seen watching the Soul Plane 2 trailer, when they distinctly hear Williams and voice of grandad, John Witherspoon (who also had an acting role in Soul Plane), having a conversation on the plane. He also voiced Sweet in The Trumpet of the Swan. Williams also appeared in the film The Factory, starring John Cusack. In 2011, Williams narrated the feature-length documentary Ayn Rand and the Prophecy of Atlas Shrugged. Perhaps his most well known role is as Melvin (a father) in House Party: Tonight's the Night. Williams played Anton Zeck/Bebop in Teenage Mutant Ninja Turtles: Out of the Shadows (2016). He voiced the demon in the horror film Truth or Dare (2018).