Belzer was born in Bridgeport, Connecticut, on August 4, 1944, to parents of Polish descent. He was a stand-up comic before he began his acting career, and his first national exposure came on "The Tonight Show Starring Johnny Carson". He is best known for his role as John Munch on the TV series "", for which he was twice nominated for a Primetime Emmy Award for Outstanding Supporting Actor in a Drama Series. Belzer's first marriage was to actress Debra Sharpe, with whom he had one daughter, actress Nadia Belzer. His second marriage was to actress Harlee McBride, with whom he had two sons, Wyatt and John M. Belzer. Belzer died on February 19, 2023, at the age of 78. A private funeral was held. He is survived by his wife, Harlee McBride; his daughter, Nadia Belzer; his two sons, Wyatt and John M. Belzer; and two grandchildren.