Grey's Anatomy lost one of its original cast members in Season 16 when Justin Chambers left the series. While he was only one of several original stars to have departed the ABC medical drama (the most notable still being Patrick Dempsey, whose Dr. Derek Shepherd was killed off), Chambers had put in more than a decade of work as Dr. Alex Karev. That meant his exit was shocking to fans, especially when they were told why the actor -- and Alex Karev -- were leaving.
Source:https://www.cbr.com/greys-anatomy-why-justin-chambers-left/