Stephen Dunham was born Stephen Dunham Bowers in Boston, Massachusetts on September 14, 1964 to Frederick Bowers and Sandra Dunham. He grew up in Manchester, New Hampshire.

He was married to actress Alexondra Lee. Dunham was perhaps best known for his role as Isaac Henderson in the hit 1999 film The Mummy. He had originally auditioned for the role of Rick O'Connell and was unsuccessful, however, director Stephen Sommers liked Dunham's acting enough to cast him as Henderson instead.