TV Peter Gallagher joins Grey's Anatomy as a doctor who knew Ellis Grey Kate Burton is set to reprise her role as Ellis Grey in season 18. By Samantha Highfill Samantha Highfill Samantha is a writer based in Los Angeles. Television is her one true love, and she tweets about it. A lot. EW's editorial guidelines Published on August 19, 2021 06:23PM EDT Paging Dr. Sandy Cohen! EW has confirmed that Peter Gallagher is joining Grey's Anatomy in season 18. The O.C. alum will play Dr. Alan Hamilton, who knew Ellis Grey (Kate Burton) back in the day and meets Meredith (Ellen Pompeo) in the season premiere. Burton is also set to appear in season 18. She'll reprise her role as Meredith's tough but brilliant mother in multiple episodes. Burton is set to first appear in the season premiere. There's no word yet on how Burton might appear, seeing as how Ellis died during the show's third season. But seeing as how season 17 introduced the idea of Meredith's oceanfront afterlife, a beach where she can interact with people she's lost, anything is possible. Although if the beach still exists, then the question becomes: Will Meredith still be battling COVID this season? Or perhaps Ellis will be featured another way entirely. Peter Gallagher. Jim Spellman/WireImage All we know is that The O.C. once made a joke about Neil Roberts (Michael Nouri) being bossed around by a short lady in Seattle, and now our heads hurt. Grey's Anatomy returns for season 18 on Sept. 30. Related content: Ellen Pompeo responds to fan who called Grey's Anatomy season 17 'dumpster fire trash' How 17 Grey's Anatomy characters left the show I'm still not over… Denny's death in Grey's Anatomy