Warren Keith Lieberstein (born September 20, 1968) is an American writer and producer. He has worked on shows such as Carpoolers and The Office, to which he has extensive ties. He is the younger brother of the show's former showrunner/actor Paul Lieberstein and brother-in-law of its developer and original producer Greg Daniels. He and Angela Kinsey (who plays Angela) were married for 8 years and have a daughter who was born in 2008.He often works with his writing partner Halsted Sullivan.