[citation needed] Sommer made his acting debut at the age of nine in a North Carolina production of Watch on the Rhine.
He made his film debut in Dirty Harry (1971) and appeared in films such as The Stepford Wives (1975), Close Encounters of the Third Kind (1977), Still of the Night (1982), Silkwood (1983), Peter Weir's thriller Witness (1985) opposite Harrison Ford (where he played a dirty cop), Target (1985), Malice (1993), Patch Adams (1998), and X-Men: The Last Stand (2006).
A kind-hearted benefactor of inner city youth hockey, he not only sends one of his best lawyers to coach the team but also donates the necessary funds for rink time, safe equipment and proper uniforms.
[3] In 1974, he appeared in the role of Roy Mills on The Guiding Light, and played George Barton in the 1983 TV version of Agatha Christie's Sparkling Cyanide.
He played a rare leading role opposite Sylvia Kristel, as the film noir-esque detective in the quirky horror comedy Dracula's Widow (1988).