O'Halloran has performed stage work with the Boomerang Theatre Company and the New Jersey Repertory Company.
O'Halloran's famous character, Dante Hicks, was named after the author of The Divine Comedy, Dante Alighieri.
O'Halloran has appeared in all of filmmaker Kevin Smith's "New Jersey" films as the character Dante Hicks or as one of his cousins.
Brian: (On theatre acting) Oh, yeah. It's the best training you can do, as an actor. To be in front of a live audience. There's no stop, wait, oh geez, what was that line again? It just sharpens your reflexes. It sharpens your interaction. And it definitely sharpens your memory because you have to know an entire show from beginning to end.