'The O.C.' Alum Peter Gallagher Is Joining Season 18 of 'Grey's Anatomy'

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Sandy Cohen (uh, we mean Peter Gallagher) is back on our small screens and he's trading the California sunshine for the Seattle rain. It's been confirmed that The O.C. alum has joined the cast of Grey's Anatomy for the show's 18th season. Gallagher has a recurring role and will appear in the season premiere on September 30th.

Gallagher will play Dr. Alan Hamilton, who knew Meredith Grey's (Ellen Pompeo) late mother, Ellis Grey (Kate Burton). Ellis died in the show's third season, but Burton has a recurring role in Season 18, so it sounds like we might be getting some flashback sequences showing the pair's relationship.

It has been confirmed that Dr. Hamilton will meet Meredith in the season premiere.

Gallagher has enjoyed continued success since The O.C. concluded in 2007, including roles on TV series like Grace and Frankie, Zoey's Extraordinary Playlist, and Law & Order: SVU.

This isn't the first time worlds have collided between Grey's Anatomy and The O.C. Ironically, the two shows aired in the same time slot during the latter's fourth and final season.

As The O.C.'s ratings lagged, writers threw in a few jokes about its rival show. As diehard fans may recall, Summer's dad, Dr. Neil Roberts, left Newport Beach in Season 4 after receiving a job offer from a "quirky" hospital named none other than Seattle Grace. Later in the season, Kaitlin Cooper asked her mom if Dr. Roberts was "still being bossed around by that short lady."

So meta!