Born in Dallas, Texas, McNamara is the son of a Ford Motor Company employee and an interior designer.

He attended Salisbury School, Columbia University, and studied at the Lee Strasberg Institute in New York.

[1] McNamara appeared in the feature films Texasville, Stella, Copycat, Surviving the Game, and Stealing Home.

On television, he portrayed Montgomery Clift in Liz: The Elizabeth Taylor Story[2] and Ricky Nelson in Nightmares & Dreamscapes: From the Stories of Stephen King, had a regular role on the Showtime series Beggars and Choosers, was featured in the television movies Doing Time on Maple Drive and Wildflower (CableACE Award nomination), and appeared in NYPD Blue and Law & Order: SVU, among other television series.

He got his start rescuing cats, dogs, and horses, and now travels the world advocating animal rights.