Peter Hermann

Hermann was born in New York City to German parents and moved to Germany when he was two months old. He lived in Germany until he was 10; he then learned English upon returning to the United States. He attended Yale University. After college, he taught high school English through Teach For America. He also worked as a fact-checker for Vanity Fair.

Hermann had brief stints on a variety of television shows that include the soap opera Guiding Light (1997–1998), the ABC Family show Beautiful People (2006) and the Lifetime original series Angela's Eyes (2006).

Since 2002, Hermann has had a recurring role as defense attorney Trevor Langan on Law & Order: Special Victims Unit.

Hermann has made appearances in several commercials, such as the anti-tobacco "Fair Enough" ads, and has been the face for Persil ProClean detergent since the late 2010s.

In 2006, he starred as Jeremy Glick in the feature film United 93.

Hermann was in the Broadway premiere of Eric Bogosian's Talk Radio, starring Liev Schreiber, and featuring fellow Law & Order: Special Victims Unit cast member Stephanie March. It began performances on February 15, 2007, in preparation for a March 11 opening; its final Broadway performance was on June 24, 2007.

He also guested on 30 Rock during its first season and starred in ABC's mid-season replacement series Cashmere Mafia as Davis Draper. In 2011, he appeared in the Broadway play War Horse, and made occasional appearances as Erin Reagan's ex-husband John "Jack" Boyle on Blue Bloods.

From 2015 to 2021, he starred in Younger. In March 2018, HarperCollins published Hermann's children's book If the S in Moose Comes Loose. He was a guest actor in season 2 of And Just Like That....

While appearing on Law & Order: Special Victims Unit, Hermann met lead actress Mariska Hargitay, whom he married on August 28, 2004, in Santa Barbara, California. They have a son. In April 2011, Hargitay and Hermann adopted a baby girl and six months later, the couple adopted a baby boy.