Olsen's first starring role was the title role in the 1999 TV movie ''
Arthur's Quest''. Soon after, he gave an Emmy submitted portrayal of a dying burn victim on NBC's
ER. His next role was a small one in HBO's
Black Cat Run. He soon landed a starring role in the Fox TV series
Get Real, playing Cameron Green. The series lasted for a year before he made his transition onto the big screen when he played
Ben Affleck's gunner in
Pearl Harbor, that was quickly followed by a leading role as Austin "The Cocky Blond Guy" in the teen send up feature film
Not Another Teen Movie. Olsen next played Jake in the teen comedy
The Hot Chick. In 2003, he won the role of Lloyd Christmas in
Dumb and Dumberer: When Harry Met Lloyd, the prequel to the hit movie
Dumb and Dumber. Olsen followed that up by playing opposite
Chris Evans for a second time in
Cellular. He starred in the yet to be released
Mojave and then joined the final season of Fox's
Tru Calling. He claimed three highly contrasting roles in 2006 and 2007 with the release of
Beerfest,
License to Wed and Zach Braff's
The Last Kiss. Olsen co-starred as Sully in the
Fox sitcom
The Loop. In 2009, he appeared in several episodes of the first season of the
Community sitcom, as Vaughn, a usually shirtless, neo-hippie student, musician, and athlete. Olsen appeared on
Will Ferrell and
Adam McKay's streaming video website
Funny or Die, with a small series of segments featuring a character called Perry Hilton, a parody of
Paris Hilton. He starred in the 2011 science-fiction horror film
The Thing. Olsen portrayed
Detective Marty Deeks on the
CBS show
NCIS: Los Angeles. His character appeared in two episodes of season one before joining the cast as a series regular in the second season. Olsen's sister-in-law,
Daniela Ruah, was one of his co-stars. Olsen is a producer of a short film
Bald from 2014 and executive producer of a documentary
Andy Irons: Kissed by God from 2018. He has his own
production company Cloud Nine Productions. In 2019 he started his first show as an executive producer picked up in production for Hulu called
Woke. Olsen made his writing debut with the season 11 episode 10 (the 250th overall episode) of
NCIS: Los Angeles titled "Mother", which aired December 1, 2019. ==Personal life==