It's a sad time for Grey's Anatomy fans. TV Guide can confirm that Justin Chambers has exited the show after playing Alex Karev for more than 15 seasons, leaving Ellen Pompeo, Chandra Wilson, and James Pickens Jr. as the only cast members who have been on the show since the pilot. According to The Hollywood Reporter, Chambers's final episode has already aired. The 300th episode, which aired on Nov. 15, was reportedly his last, though the storyline on the show says that Karev is just on family leave, taking care of his mother in Iowa.

"There's no good time to say goodbye to a show and character that's defined so much of my life for the past 15 years," Chambers said in a statement to Deadline. "For some time now, however, I have hoped to diversify my acting roles and career choices. And, as I turn 50 and am blessed with my remarkable, supportive wife and five wonderful children, now is that time."

Chambers has played Alex Karev on the hospital drama from the first episode. His exit means that Meredith Grey (Pompeo) is the only one of her intern class to still be at Grey Sloan Memorial after a decade and a half. It will also have huge implications, as Alex has been married to Jo (Camilla Luddington) for the past two seasons and at the beginning of Season 16 took over a hospital of his own. The couple have pitched leaving Seattle on the show, but it remains to be seen how this departure will affect Jo and her current fellowship.

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Chambers thanked ABC, Grey's creator Shonda Rhimes, his longtime co-stars, and others in his statement for his tenure on the show. "As I move on from Grey's Anatomy, I want to thank the ABC family, Shonda Rimes, original cast members Ellen Pompeo, Chandra Wilson and James Pickens, and the rest of the amazing cast and crew, both past and present, and, of course, the fans for an extraordinary ride," he said.

Grey's Anatomy returns Thursday, Jan. 23 at 9/8c on ABC.

(Disclosure: TV Guide is owned by CBS Interactive, a division of ViacomCBS)

Justin Chambers, <em>Grey's Anatomy</em>Justin Chambers, Grey's Anatomy