"Monsters University" takes us back in time to when Mike and Sully first meet as college roommates at M.U.
"I tell you, I love this guy so much. This is my favorite character of anyone I've ever played in any movie," says Billy.
Billy reunites with John Goodman for this prequel.
"The idea that they would be 18 years old was so brilliant because when the kids who saw this movie first, back in 2001, they were six and seven years old. So now they're the same age as we are. So it's a whole big audience of college people who are going to want to see this movie because, you know, it's about them now," says Billy.
More Mike. More Sully. More fun.
"I'm so blessed to work with John Goodman and we've worked together so we're really acting together. It's just a joy because he's so good that it makes the two guys in the movie very real," says Billy.
"They're not monsters to us," Billy says. "Our heart and souls are in these guys when we do them. And we get to play some very touching scenes in this movie besides being funny, because they're discovering who they are."
With "Monsters University," Billy becomes a 65-year-old teenager.
And he's got a new book about men and the aging process coming out this fall called "Still Foolin' 'Em." But for now, he's focused on "Monsters University."
Billy says the first one, "Monsters, Inc." helped his grandkids understand his career.
"They couldn't see the orgasm scene in 'Harry and Sally' and make sense of that so this was the way -- so I was 'Grandpa Mike' for about a year. I had to be Mike Wazowski for them all the time," says Billy.