Jennifer Garner
The actress played a graduate student who has a romantic encounter with Benjamin Bratt's character in a 1996 episode.
Adam Driver
Before his breakout role on Girls, Driver appeared on Law & Order's final 2010 season and played a lab technician accused of murdering an escort.
Julia Roberts
In 1999, while she was dating series star Benjamin Bratt, the actress made a rare TV appearance as a party planner involved in the death of powerful businessman.
Sebastian Stan
Nearly 20 years ago, the Pam & Tommy star played a boy abducted and raised by his abuser in 2003.
Allison Janney
Early in her career, the Oscar winner popped up on Law & Order twice in 1992 and 1994. The first time, she played a character scared to testify about a murder. She returned two years later to portray someone interviewed about the murder of soap opera actress.
Sam Rockwell
The Oscar winner has portrayed two different characters on seasons two and three, playing a police officer and a member of a family accused of murdering a Chinese-American student respectively.
Emmy Rossum
Rossum's very first acting gig was on a 1997 episode playing a preteen who was the target of a female circumcision.
Sarah Paulson
In her very first TV role, the Emmy winner played a teen who claimed that she was having an affair with her murdered mother's new husband in 1994.
Samuel L. Jackson
The actor appeared in a 1991 episode as the lawyer for a drug dealer accused of rape. Who played the drug dealer? Read on...
Philip Seymour Hoffman
In his first television role, the future Oscar winner played a drug dealer betrayed by another crook. Samuel L. Jackson is his lawyer.
Claire Danes
Even before her starring role on My So-Called Life, the actress played a troubled teen in a 1992 episode that also featured future Six Feet Under star Lauren Ambrose.
Leighton Meester
In a 1999 episode, she plays the daughter of a battered woman who helps detectives Briscoe and Curtis with a case.
Vera Farmiga
The Up In the Air star had a part in a 1998 episode about a shooting.
Ellen Pompeo
The Grey's Anatomy actress actually appeared on Law & Order twice, in 1996 and 2000. (Fellow Grey's stars Kate Walsh and Chandra Wilson also got work on the series.)
Cynthia Nixon
During the show's first season, the actress played a woman who shoots two men in a subway.
Amanda Peet
In 1995, Peet played a woman involved in a mysterious case.
Chandra Wilson
Decades before Grey's Anatomy, Wilson played Serena Price for one 1992 episode.