Actor Patrick Dempsey. Picture: AP Photo/Francois Mori

Patrick Dempsey has admitted her left 'Grey's Anatomy' after 10 years because he lost interest in the show.

The 52-year-old actor played Dr. Derek 'McDreamy' Shepherd in 252 episodes from 2005 to 2015 but made the decision to walk away from the ABC medical drama because he needed a fresh challenge in his career.

In an interview with The I Paper, he said: "Look, 10 years is a long time to be on any show. It's very hard to keep the storylines intriguing, especially on a network show with 25 episodes a year. So for me, it was time to go ... it's nice to move on and have new challenges."

Dempsey said goodbye to Dr. Shepherd for good when his alter ego was shot dead, however, some fans still have hope he will return to the role, despite the character's fatal end.

He said: "They want me to come back to the show which, given what happened to Derek, is really quite funny."

Although he accepts that he'll always be best known for playing Dr. Shepherd, Dempsey hopes his fans also appreciate his more recent projects, such as his appearance in rom-com sequel 'Bridget Jones's Baby', and will get behind his new work.

Dempsey - who will next be seen in TV miniseries 'The Truth About the Harry Quebert Affair' - said: "You want to keep being able to surprise the audience, then hopefully you take your core audience from Grey's Anatomy, stretch them and make them come on a journey with you. Constantly improving as an artist."