(written from a Production point of view)
Sheehan attended Yale University in New Haven, Connecticut, where he played football in addition to acting. He performed in several plays for Yale Dramatic Theatre, including productions of Tennessee Williams' Orpheus Descending and Anton Chekhov's Three Sisters. He also acted in a number of student films. He graduated from Yale with a Bachelor of arts degree in Sociology and Theatre Studies in 2003, after which he moved to Los Angeles to continue his acting career.
He made his feature film debut in the independent romantic comedy Red Thread, shot in Louisville, Kentucky, and produced by Stratton Leopold. He then had lead roles in the short films Firm and Willets Point Station (aka The Red Line). Star Trek was his first major studio film.