: Addison Montgomery-Shepherd arrives, revealing Derek is married.
The season one finale of Grey's Anatomy , titled "Who's Zoomin' Who?," originally aired on May 22, 2005. The episode is famous for its massive cliffhanger: the arrival of Addison Montgomery, Derek’s secret wife. Eps9Greys Anatomy - Season 1
While the interns gossiped about the outbreak, Izzie and Cristina were caught in their own ethical storm. They performed an unauthorized autopsy on a patient to prove his death wasn't their fault, eventually discovering a genetic condition that saved the man's daughter. Meanwhile, Derek was busy performing a secret surgery on Chief Webber, who was struggling with a brain tumor that threatened his eyesight. : Addison Montgomery-Shepherd arrives
: Derek operates on Chief Webber's brain tumor in secret. titled "Who's Zoomin' Who?