"Thriller" is the seventh episode of the tenth season of Grey's Anatomy and the 203rd produced episode of the series. It is also the 314th produced episode of the Grey's Anatomy franchise. It was broadcast on October 31, 2013.
It's Halloween at Grey Sloan Memorial Hospital and a series of spooky patients test the doctors as Meredith's attempts to juggle motherhood and her career further distance her from Cristina while Richard's attempts to teach the second year residents with his injuries cause friction with Bailey after he requests she choose one of them, and not her, to perform his surgery and Ben returns with a surprising revelation. A patient causes Callie to reconsider how her animosity towards her wife is affecting her daughter while, after developing a physical connection, Leah tries to keep her relationship with Arizona 'easy peasy' until she's faced with a life-altering crisis. Shane continues to be haunted by Heather when one of her old patients arrives in the E.R and Jo finds her relationship with Alex on the brink of extinction as he continues to push her away.
- "Every Halloween we make a choice about what kind of costume we're going to wear. Something sexy? Maybe we'll be someone scary? Or you could be a superhero, which is what I'm trying to be this year."
- "Halloween is not for the faint of heart. There's a surprise around every corner. Some of the surprises are good and some of the surprises are bad. What's important is you can't let the fear of the surprise stop you from getting dressed up and wandering up to a strangers house to ask the question. So what will it be? Trick or treat?"
- "Change" - Banks
- "Sun" - Sleeping At Last
- "Inner Ninja" - Classified feat. David Myles
This episode's title originated from the song Thriller, originally sung by Michael Jackson.