Bethesda's own blog had New Vegas senior producer Jason Bergman share some anecdotes and introduce us to the various actors cast to voice the game.
Matthew Perry as Benny
Matt first got on our radar because he went on talk shows the first being Ellen and one of his anecdotes was that he played so much Fallout 3 that he had to get surgery on his wrist. In fact, he even gave an Xbox 360 and a copy of Fallout 3 to Ellen, I believe. So we contacted him to see if he would be interested, as we had a role that we thought would be a really good fit for him.
After reaching out we had a meeting with Matt where it was me, him, a couple people from Obsidian, and people from the talent agency. The conversation basically just descended into nerdiness. He just wanted talk about Fallout 3, and gaming in general. That guy is not faking it he is really that into Fallout 3 and games in general. It was cool; you can tell when someone is genuinely enthusiastic.
Voice-wise and attitude-wise, think of Benny as the lost Rat Pack character. He's the head of the Chairmen, who run the Tops casino. His character has his own agenda. Matthew Perry really dove head-first into his role, and that was not easy; there's some Rat Pack slang in there.