Episode: Season 6, Episode 23 and 24
What happens: The shooting episodes make up one of Grey's Anatomy's most tragic and unsettling arcs. Basically, a late patient's husband goes into the hospital armed and begins shooting staff members, including Derek, Owen, and Alex. The casualties who aren't so lucky are Reed and Charles, two new resident transfers from Mercy West. In "Sanctuary," Gary shoots Reed in the head and Charles in the chest. Doctor Bailey tries to save the latter in "Death and All His Friends," but the lifts don't work so she can't get him help in time. It's in this episode where we first see Mandy Moore emotionally crush us on primetime. The This Is Us actress plays Doctor Bailey's patient Mary, who assists the surgeon with helping Charles.