Seven years after being let go from the ABC hit drama for reportedly using a homophobic slur on set and later at the Golden Globes, Washington will reprise the role of Dr. Preston Burke to help bring Cristina Yang's journey "full-circle" before Sandra Oh exits the series.
When George Clooney left ER, we were heartbroken, but perhaps not as much as his TV girlfriend Carol Hathaway (Julianna Margulies). Clooney departed in season five of the long-running drama, but made a surprise—seriously, it was kept under wraps so well!—appearance in Margulies' last episode in season six. The two also returned to the NBC medical drama during the 15th and final season.
No, we still aren't over OUAT killing off Sheriff Graham aka Hot Hipster Sheriff after just seven episodes. But the man who would go on to be Fifty Shades of Grey's leading man would make two brief returns to Storybrooke, most recently in season two. And fans almost got to see him again, as producers had a big plan for Dornan's return, but scheduling conflicts quashed a potential season three appearance.
After Carell left Dunder-Mifflin behind in season seven when his contract was up, the NBC hit sitcom just wasn't the same without Michael Scott, which is why his surprise return in the series finale (Delivering one final "That's what she said") was so special.
After 12 years as Catherine Willows, Helgenberger devastated CSI fans when she chose to leave the show behind to pursue more theater work. Fortunately, Helgenberger returned for the procedural's big 300th episode in October 2013.
The prodigal son returns! Murray, who left the CW series along with Hilarie Burton in season six, returned for its ninth and final season, delighting Lucas Scott fans everywhere. Burton did not return, as Peyton decided to stay in Australia with their son, Sawyer. (We all lived.)
Duchovny left the hit series in its seventh season after intense contract negotiations and a lawsuit with 20th Century Fox, enraging fans invested in Mulder and Scully's relationship. Still, he appeared in 12 episodes of season eight to fulfill his contract, but only returned in season nine for the series finale. He also co-wroteand directed a season nine episode, "William."
Arguably one of TV's most controversial returns of all time, Duffy returned to the hit soap in 1986, a full season after his beloved character Bobby Ewing had been killed off. So why was his return so controversial? It was all a dream as his wife, Pam (Victoria Principal), woke up to find Bobby in the shower. Almost 20 years later, people are still talking about the crazy twist.
In the criminal justice system, we've had many Law & Order: SVU ADAs, but Alexandra Cabot was certainly a fan-favorite. March, who joined SVU in season two, left the series in season five. Alex Cabot went into witness protection after faking her death. She returned in season six, but then disappeared again only to show up in the short-lived Conviction TV series. March reprised the role of Cabot on Law & Order: SVU once again in seasons 10, 11 and 13.
Doctor Who fans all over the world were devastated when David Tennant (or Ten, as he's often lovingly referred to) left his time as the Doctor behind in a special following the end of season four, as he saved Donna's (Katherine Tate) beloved grandpa Wilfred from death by radiation. His last words ("I don't want to go.") were heart-wrenching, but all was made temporarily well when he showed up in the 50th anniversary special to marry Queen Elizabeth I, hang out/save Gallifrey with two other versions of himself and break our hearts all over again.
Though the fan favorite permanently exited the show after its seventh season after a brief season six hiatus, her character Emily Prentiss made her highly anticipated return for its recent milestone episode. "Our 200th episode is going to be a special show," Erica Messer, Criminal Minds' showrunner, said in a statement. "We can't imagine telling this story without Paget being present."
Head, who played Buffy's Watcher/father figure/mentor Giles, exited the WB cult hit in season six so he could spend more time with his family in England. (Giles also jetted off to England after realizing Buffy was too dependent on him. Sniff!) However, Giles just couldn't stay away from Sunnydale, first returning to stop Willow from destroying the world and later coming back with a group of potential Slayers.
After his beloved Castiel was killed off in season eight, the CW drama brought him back after receiving some heat from fans. After being bumped back up to a series regular for season nine, Collins tweeted, "I don't think the feathers to the offices campaign was what saved the angel, but it does look like i'm going to be a regular for season 9." Lesson learned: Every time a tweet is tweeted, an angel gets his wings...back.
PHOTOS: Famous Feuds: TV Stars vs. TV Shows