Addison MontgomeryPlayed by: Kate Walsh
A highly regarded neonatal surgeon and a fellow of the American College of Surgeons, Addison Forbes Montgomery is a board certified OB-GYN with fellowships in maternal-fetal medicine and medical genetics.
She also completed two years of study on cystic fibrosis. In addition, she is also one of only a handful of surgeons in her field who know how to successfully separate fetal blood vessels.
Addison was married to a fellow doctor, brain surgeon Derek Shepherd, for over 10 years before sleeping with his best friend, plastic surgeon Mark Sloan, prompting Derek to leave their life in New York for Seattle.
In spite of her specialty, Addison admitted to Miranda Bailey of Seattle Grace, where she eventually followed Derek in hopes of reconciling, that when she and Derek discussed having children, she wasn't ready.
After she and Derek initially separated, she remained in New York and lived with Mark for two months, during which she became pregnant with Mark's baby and had an abortion.
The relationship ended when Mark cheated on Addison and Dr. Richard Webber brought her to Seattle Grace to help with a rare, difficult Twin-to-Twin Transfusion Syndrome case (and, presumably, given the nature of Richard's relationship with Meredith Grey, to break Derek and Meredith up).
Richard, the Chief of Surgery at Seattle Gracae, once taught Addison. She once avoided him for almost a year after he taught her not to get close to her patients by assigning her to a case in which he knew the patient would die.
After a period of antagonism between her and Derek, Addison then decided to stay on as head of neo-natal surgery at Seattle Grace, signing a two-year contract after she and Derek decided to work things out.
But after finding out that he slept with Meredith at the hospital-sponsored prom, Addison (in a drunken haze) called Mark Sloan to Seattle. Derek and Addison then agreed it was over and started divorce proceedings.
She asked Mark to go back to New York, but he stayed, expressing his desire to continue their relationship. Addison rebuffed Mark, while eventually, in the spirit of coming, divulged the whole truth regarding her infidelity to Derek which led to an emotionally charged encounter in which Derek told her to get out of his life.
A possibility of a relationship between her and intern Alex Karev loomed, even after he rejected her affections on more than one occasion. At the same time, Mark continued to lust after her from afar.
Addison challenged Mark to abstain from sex for 60 days, saying she would give him a chance at a real relationship with her if she could do it. Yet it was her who failed in the end, sleeping with Karev.
She is spared from confessing, however, when Mark - having figured out what was going on - lies to her by telling her he had broken their promise and was not worthy of her. Addison then decides to pursue Karev, but is again rejected.
Realizing Mark is never going to be who she wants him to be, and having been spurned by Alex, she takes a road trip to Los Angeles to visit Naomi and Sam, her old friends from medical school.
There, she learned that she can no longer conceive, as her antral follicle count was negligible. However, despite that obvious heartbreak, she soon realized that a permanent vacation to Southern California and her friends at the Oceanside Wellness Group might be just the prescription she needs -to get her life back on the right track.