In the 17 seasons that Law & Order: SVU has been on the air, there have been countless celebrity guest stars. Some were already super-famous when they played a baddie (see Robin Williams and Martin Short), but others were just getting started. Take a look back at these 10 actors who you might not have realized committed some of TV's "especially heinous" crimes.
Ian Somerhalder (Season 4, Episode 20)
Before he played Damon Salvatore on The Vampire Diaries or Boone Carlyle on Lost, Ian Somerhalder was Charlie Baker, a killer, rapist, and kidnapper who manipulated his brother into killing people.
Kyle MacLachlan (Season 6, Episode 6)
He played Dr. Morton, the father of a boy who was murdered by their 13-year-old neighbor. After hearing the sentence of his son’s killer, Dr. Morton shot him point blank in the courtroom. Kyle MacLachlan is also known for Sex and the City, Portlandia, Desperate Housewives, and Twin Peaks (which he'll be reprising in the upcoming Showtime reboot).
Sarah Hyland (Season 10, Episode 12)
Before becoming Haley Dunphy on Modern Family, Sarah Hyland was on SVU, playing a tightly wound prep school student, Jennifer Banks, who murdered her roommate after learning that the victime was getting better grades.
Kate Mara (Season 2, Episode 9)
Before she joined the casts of House of Cards as Zoe Barnes or The Martian as Beth Johanssen, Kate Mara played competitive gymnast, Lori, who killed a fellow athlete with a brick after getting her place on the team.
Chad Lowe (Season 2, Episode 20)
Rob Lowe’s younger brother played murderous security guard, Jason Mayberry, on SVU years before joining the cast of Pretty Little Liars as Byron Montogomery.
Robin Williams (Season 9, Episode 17)
Though he was already a huge star from movies like Good Will Hunting, Dead Poets Society, and Mrs. Doubtfire, Robin Williams' role as anti-authority audio engineer Merritt Rook in SVU won a People’s Choice Award and was nominated for an Emmy.
Martin Short (Season 6, Episode 18)
Martin Short was also a big star before he went on Law & Order: SVU to play a serial rapist and murderer from Canada who crossed the border, changed his name, and acted like a psychic to help provide the SVU squad with information on the crimes he was actually committing. Quite the difference from Short’s usual scene on Saturday Night Live, Curb Your Enthusiasm, or Three Amigos!
Pablo Schreiber (Season 14, Season 15)
Pablo Schreiber played a multi-episode arc as William Lewis, a sadistic serial killer and rapist, who most notably kidnapped and tortured Det. Olivia Benson, whom he became obsessed with during her investigation of his other crimes against women. You might also know Schreiber as "Pornstache" in Orange Is The New Black or JB Bellmiere on our own White Collar.
Kal Penn (Season 8, Episode 12)
Though he may be best known for playing Kumar in Harold & Kumar Go To White Castle, Kal Penn played a more serious role in SVU: Henry Chanoor, a janitor who was also a serial rapist and killer. Like many of the killers in SVU, Henry Chanoor felt like he was the ignored black sheep of his family.
Justin Kirk (Season 3, Episode 2)
Before playing Uncle Andy in Weeds, Justin Kirk played a serial killer who sought vengeance against Det. Benson after she handled a case that led to his wrongful imprisonment. Once out of prison, however, he murdered multiple people connected to cases that Benson had investigated.