Rob Lowe Turned Down Playing McDreamy in Grey's Anatomy

The role that made Patrick Dempsey a star was originally offered to Rob Lowe, who chose a different show instead.

Published on Feb. 24, 2026

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It's hard to imagine anyone other than Patrick Dempsey playing the iconic role of Derek Shepherd, a.k.a. McDreamy, on the long-running medical drama Grey's Anatomy. However, it turns out Rob Lowe was the network's first choice for the part, but he ultimately chose to star in the short-lived CBS series Dr. Vegas instead. The decision proved to be a pivotal moment, as Dempsey's portrayal of Derek went on to become a defining role in his career and a fan-favorite character on the show.

Why it matters

The casting of Derek Shepherd was a crucial decision that shaped the trajectory of Grey's Anatomy and Patrick Dempsey's career. If Lowe had accepted the role, the show and character may have turned out very differently, potentially altering the course of the series. This behind-the-scenes story provides insight into the network's initial vision for the show and how serendipitous it was that Dempsey ultimately landed the part.

The details

According to an excerpt from the book How to Save a Life: The Inside Story of Grey's Anatomy, the network wanted Lowe to play Derek Shepherd, but he chose to star in the CBS series Dr. Vegas instead. The producers then turned to Patrick Dempsey, who at the time was not the network's first choice, but they felt he was the right fit for the role. Dempsey's portrayal of Derek Shepherd went on to become a fan-favorite and a defining part of his career, while Lowe's Dr. Vegas was canceled after just five episodes.

  • In the early 2000s, the network wanted Rob Lowe to play Derek Shepherd on Grey's Anatomy.
  • Lowe chose to star in the CBS series Dr. Vegas instead of taking the role on Grey's Anatomy.
  • The producers then cast Patrick Dempsey as Derek Shepherd, a decision that proved to be pivotal for the show and Dempsey's career.

The players

Rob Lowe

An American actor who was the network's first choice to play Derek Shepherd on Grey's Anatomy, but he ultimately chose to star in the short-lived CBS series Dr. Vegas instead.

Patrick Dempsey

The actor who was cast as Derek Shepherd, a.k.a. McDreamy, on Grey's Anatomy, a role that became a defining part of his career and a fan-favorite character on the show.

Peter Horton

An executive producer on Grey's Anatomy who revealed that the network initially wanted Rob Lowe for the role of Derek Shepherd.

Les Moonves

The former chairman of CBS Corporation who made a personal pitch to Rob Lowe that convinced him to choose the CBS series Dr. Vegas over Grey's Anatomy.

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What they’re saying

“The network wanted us to cast Rob Lowe as Derek Shepherd. He's not exactly who we had in mind for McDreamy, but we met with Rob. He had a choice of either doing our show or Dr. Vegas for CBS. He chose Dr. Vegas.”

— Peter Horton, Executive Producer, Grey's Anatomy (EW)

“My picker was awesome! The real, honest reason was [former CBS Corporation chairman] Les Moonves's pitch to me. His personal pitch was amazing, and there was no pitch from ABC. ABC just never said anything. I just had a better meeting with CBS. The scripts were incomparable. The vibe around Dr. Vegas was great. The script for Grey's Anatomy was great. I went with the vibe over the script. The rest, as they say, is McDreamy.”

— Rob Lowe (EW)

What’s next

It's unclear if Patrick Dempsey will ever return to Grey's Anatomy again, especially with his new show Memory of a Killer on the 2026 TV schedule. However, fans would love to see Rob Lowe make a guest appearance on the long-running medical drama, even if just for an episode, to fulfill the 'what if' scenario of him playing Derek Shepherd.

The takeaway

The casting of Derek Shepherd on Grey's Anatomy was a pivotal moment that shaped the show and Patrick Dempsey's career. While Rob Lowe was the network's initial choice, Dempsey's portrayal of the character became iconic and a fan-favorite. This behind-the-scenes story highlights how serendipitous it was that Dempsey landed the role, and how the show may have turned out differently if Lowe had accepted it.