Authorities said a coworker went to check on him at his home in the 5400 block of Tujunga Avenue at about 9:15 a.m. after he did not show up for work on TNT's crime drama "Rizzoli & Isles."
The 29-year-old actor had a self-inflicted gunshot wound to his head, police said. He was pronounced dead at the scene.
"Lee was more than just a brilliant young actor," Paul Baruch, his manager, said in a statement. "He was a wonderful and gentle soul who will be truly missed. We ask that you please respect the privacy of his family and friends as this very difficult time."
Young began his career as the star of the Disney Channel's "The Famous Jett Jackson" which aired from 1998 to 2001. He was also featured in the film "Friday Night Lights," and most recently, he played a police detective on "Rizzoli & Isles."
"Everyone at Rizzoli & Isles is devastated by the news of the passing of Lee Thompson Young," TNT, Warner Bros. and Rizzoli & Isles executive producer Janet Tamaro said in a statement. "We are beyond heartbroken at the loss of this sweet, gentle, good-hearted, intelligent man. He was truly a member of our family."
The Associated Press contributed to this report.