ET confirms that T.R. Knight is leaving "Grey's Anatomy."

"Leaving 'Grey's Anatomy' was not an easy decision for me to make," T.R. tells ET. "I am extremely grateful to have had the opportunity to play this character and will miss my fellow cast and crew very much. I continue to wish them the very best, and wholeheartedly thank all of the fans who have supported me and the show with such passion and enthusiasm."

Meanwhile, series creator and head writer Shonda Rhimes says, "I think I speak for the entire 'Grey's Anatomy' family when I say we wish T.R. Knight the best in his future endeavors. He is an incredibly talented actor and a person whose strength of character is admired by all of us."