Trying to find a voice actor?

There's a voice actor who had a regular role on Animaniacs. He also had a cameo in The Boondocks as Uncle Ruckus' father in the episode "The color of Ruckus". I tried IMDB and it doesn't have a complete cast list for that episode, and I don't know what role he had on Animaniacs. I just recognize the voice. How do I find him?