Peter and his fiancée, Maggie Gyllenhaal, became the parents of a girl, named Ramona, on October 3, 2006 in New York City.

He attended the Actors' Studio Program at Washington University in St. Louis, Missouri.

His baby face; his soft, strangely ominous voice; and often bizarre, unstable characters have led to him being compared to John Malkovich, who played his father in The Man in the Iron Mask (1998/I).

In Garden State (2004), Peter's character collects Desert Storm trading cards. In Jarhead (2005), Peter's character fights in Desert Storm.

Like Edward Norton and Broadway actress Kimmilee Bryant, he studied with legendary acting coach Terry Schreiber at the T.Schreiber Studio in New York.

Engaged to Maggie Gyllenhaal [April 2006]

Childhood hero was Dallas Cowboys running back Tony Dorsett.

Formerly dated model/actress Shalom Harlow (2001).