Rothlaar was born in New York City, the son of Michael Rothhaar and Nancy Linehan Charles, both of whom are playwrights, actors and directors.
[1] He briefly lived in the little resort town of Boiling Springs, Pennsylvania, where he started doing theatre, but grew up on the west side of Los Angeles and attended Alexander Hamilton High School.
[2] Rothhaar began acting in the mid-1990s, and appeared in several made-for-television films and series, including Buffy the Vampire Slayer and Mad About You.
He had supporting roles in several feature films, including Jack Frost and Hearts in Atlantis.
In 1999, he received The Hollywood Reporter "Young Star Award" for his portrayal of John in David Mamet's The Cryptogram at the Geffen Playhouse.