Michael Jonathan Zegen (born February 20, 1979) is an American actor. He is best known for his roles in the television series Rescue Me (2004–2011), Boardwalk Empire (2011–2014), and The Marvelous Mrs. Maisel (2017–2023).

Zegen was born to a teacher mother and a lawyer father, and lived in Glen Rock, New Jersey, before moving to nearby Ridgewood when he was five. He has two brothers. He is Jewish. His mother was born in Austria in a displaced persons' camp, and his maternal grandparents were Holocaust survivors from Ukraine and Poland. He attended Ridgewood High School, where he was active in the school's theater program. Zegen is a 2001 graduate of Skidmore College.