Peter MacNicol (born April 10, 1954) is an American actor. He is known in films for his roles of Janosz Poha in Ghostbusters II, Stingo in Sophie's Choice, and David Langley in Bean. For television he is known for the roles of the eccentric lawyer John Cage in the FOX comedy-drama Ally McBeal, as Tom Lennox in the sixth season of action-thriller 24, Alan Birch in the medical drama Chicago Hope, and as physicist Dr. Larry Fleinhardt on the CBS crime drama Numb3rs.