 The series follows Meredith Grey ( Ellen Pompeo ) , the daughter of an esteemed general surgeon named Ellis Grey , following her acceptance into the residency program at the fictional Seattle Grace Hospital . During her tenure as a resident , Grey works alongside fellow doctors Cristina Yang ( Sandra Oh ) , Alex Karev ( Justin Chambers ) , Izzie Stevens ( Katherine Heigl ) , and George O 'Malley ( T. R. Knight ) , who each struggle to balance their personal lives with the hectic work and training schedules assigned to them . They are overseen during their internship by Miranda Bailey ( Chandra Wilson ) , a senior resident who works beneath Grey 's love @-@ interest Derek Shepherd ( Patrick Dempsey ) , the head of neurosurgery ; Yang 's fiancee Preston Burke ( Isaiah Washington ) , the head of cardio ; and Ellis Grey 's ex @-@ lover Richard Webber ( James Pickens , Jr . ) , the Chief of Surgery . The residents are later joined by Jackson Avery ( Jesse Williams ) and April Kepner ( Sarah Drew ) , former Mercy @-@ West residents who join Seattle Grace following an administrative merger in the sixth season . Throughout the first six seasons O 'Malley , Burke and Stevens all depart the series which has become very controversial in the media over the life @-@ span of the series . In addition to Shepherd , Webber , and Burke , the surgical wing is primarily supervised by Owen Hunt ( Kevin McKidd ) , as head of trauma ; Arizona Robbins ( Jessica Capshaw ) , as head of pediatric surgery ; Callie Torres ( Sara Ramirez ) , a resident who later becomes head of orthopedics , who left Seattle at the end of the twelfth season ; Erica Hahn ( Brooke Smith ) , as head of cardio ; Mark Sloan ( Eric Dane ) , as head of plastics ; Addison Montgomery ( Kate Walsh ) , as head of OB / GYN , neonatal , and fetal surgery ; Teddy Altman ( Kim Raver ) , as head of cardio ; and Amelia Shepherd ( Caterina Scorsone ) , Derek 's sister who is hired to replace him as head of neuro . Derek is killed in the series ' eleventh season . 
