The episode in which Derek Shepherd (Patrick Dempsey) dies is one that most Greys Anatomy fans will never forget. The fateful incident occurred in season 11, episode 21, and it was titled, How To Save a Life.

The attending doctor who failed to save McDreamys life recently appeared in an episode of Greys Anatomy. Lets take a look at who he is and what happened. Warning: Season 16 spoilers.

One fateful night, Dr. Derek Shepherd is on his way to Washington to quit the Presidents brain-mapping project. He sees a car accident and pulls over to help. He saves a young girl, her mother, and another couple that was involved in the crash. Just as Derek is about to leave the scene, he is hit by a semi-truck.

McDreamy is rushed to the nearest ER, unable to speak. As the doctors examine him, Shepherd is subconsciously telling them that he needs a head CT scan. However, he is rushed right into surgery. Dr. Penelope Blake (Samantha Sloyan) wants to perform a CT but is dismissed by her attending, Dr. Paul Castello (Mike McColl).

By the time the doctors discover his blown pupil, Shepherd realizes he is about to die. The neurosurgeon arrives at the OR too late, and to the dismay of viewers at home, McDreamy is pronounced brain dead.

Dr. Paul Castello, who refused to do the head CT, is played by Mike McColl. The actor was only in two episodes of Greys Anatomy.

McColl grew up in North Carolina, but moved to Los Angeles in 1996 to study at the American Academy of Dramatic Arts. His first professional audition helped to land him the title role in an MTV comedy pilot, Normal Joe.

He then landed the voiceover role in the movie, Love and Basketball. Since then, he has voiced numerous movie trailers and TV promos. He also performs as the narrator for a variety of TV programs and documentaries.McColl is married and has two children.

When he starred in Greys Anatomy, he tweeted, McDeadly. He told friends and family to watch the show, particularly because it is usually just his voice on TV shows. If fans of the show had seen his tweet, they would have been in an uproar. Maybe that is why the producers did not choose a big name actor to be the one who killed our beloved, McDreamy.

McColl returned to the medical drama for season 16, episode eight, My Shot. He appears again as Dr. Paul Castello, but this time he is on the medical board that is to decide if Meredith Grey (Ellen Pompeo) gets her medical license back.

Half-way through the episode, Meredith can not keep her mouth shut any longer (although her lawyer insists she not talk at all). When Dr. Castello tries to question Meredith, she stands up and starts yelling.

You are the coward who stood over my dying husband and refused to drill bur holes, refused to do a head CT, Meredith gets closer to him. You dont deserve to judge anyone.

When she stops yelling, he collapses into a seizure. The doctors call 9-1-1, and he is rushed to Grey Sloan Hospital. The seizures stop, and Amelia Shepherd (Caterina Scorsone) takes him in for a head CT. The surgeons determine that he needs a craniotomy. Dr. Tom Koracick (Greg Germann) performs the surgery, but Dr. Castello does not make it.

In true Greys Anatomy fashion, the doctor who let Derek die without a CT of his brain, then dies during brain surgery.

Link:
'Grey's Anatomy': Who is the Attending Doctor That Killed Derek 'McDreamy' Shepherd?Why is he back? - Showbiz Cheat Sheet