It feels like it was yesterday when Peter Capaldi replaced Matt Smith as the legendary Doctor. But like Smith and David Tennant before him, Capaldi will set down his sonic screwdriver after three seasons on "Doctor Who" after this year's Christmas special Of course, that means that the Doctor will soon undergo another regeneration, an event which has occurred 12 times over the decades with various results. With the identity of the 13th Doctor about to be announced, here are our picks for the best and worst farewells The Doctor has given.

12. David Tennant as the 10th Doctor in "The End of Time" Matt Smith's tenure as the Doctor got off to a rocky start thanks to David Tennant ending his run as one of the most popular Doctors ever by infamously wailing "I don't want to go!" Tennant's last "Who" tale consisted of the Doctor treating regeneration like permanent death, only to giddily hop around once he transformed into the Eleventh Doctor. Combine that with a new show runner that overhauled the show, and you have a very dissonant jump from one era of "Doctor Who" to the next

11. Colin Baker as the Sixth Doctor in "Time and the Rani" Unlike the other Doctors, Colin Baker unceremoniously left "Who" in between seasons, forcing an impromptu regeneration in 1987 that required Sylvester McCoy to wear a wig imitating Baker's curly locks for the regeneration scene.

10. Sylvester McCoy as the Seventh Doctor in the "Doctor Who" TV Movie The maligned attempt by Fox to resurrect "Doctor Who" in the '90s featured McCoy dying a gruesome death in an emergency room -- complete with grisly sound effects -- before regenerating into Paul McGann's Eighth Doctor.

9. Patrick Troughton as the Second Doctor in "The War Games" In return for helping save some enslaved human soldiers, the Doctor turns himself in to his fellow Time Lords to be tried for stealing his time-traveling TARDIS. As punishment, the Doctor is forced to regenerate in a rather silly sequence where he blubbers about the possible new bodies he might be forced to inhabit.

8.)Tom Baker as the Fourth Doctor in "Logopolis" The most iconic Doctor ever ended his run after falling from a crane during a battle with his archnemesis, The Master. Though the effects showing the Doctor's transformation into his boyish fifth incarnation look weird by today's standards, this episode did give Baker some beautiful last words: "It is the end...but the moment has been prepared for."

7. William Hartnell as the First Doctor in "The Tenth Planet" This regeneration may be a simple white flash that switches the face of Hartnell with that of Patrick Troughton, but make no mistake: this is an important moment in "Doctor Who" history, as it establishes the concept of regeneration that allowed "Doctor Who" to last for 50-plus years.

6. John Hurt as the War Doctor in "The Day of the Doctor" The late, great John Hurt left a short but unforgettable mark on "Doctor Who" history in the series' 50th anniversary special, playing a Doctor who did such unspeakable things that later incarnations considered him unworthy of his name. But Hurt's Doctor found redemption before peacefully letting go of his form...but not before joking about his next incarnation's massive ears.

5. Jon Pertwee as the Third Doctor in "Planet of the Spiders" Pertwee's Doctor was known for offering compassion and sage advice to his companions. That generous spirit carried through to the end, as he used his final words to console a tearful Sarah Jane Smith.

4. Paul McGann as the Eighth Doctor in "The Night of the Doctor" After Fox declined to revive "Doctor Who" when McGann's TV movie flopped in the U.S., the Eighth Doctor's adventures were mostly confined to radio serials. But in 2013, McGann returned for a mini-episode prologue to the 50th anniversary special, and his performance and regeneration were so excellent that Whovians called for BBC to put McGann in a spinoff.

3.Christopher Eccleston as the Ninth Doctor in "The Parting of the Ways" After a new generation of viewers embraced the show's return in 2005, Christopher Eccleston had to teach them to accept a new Time Lord. Eccleston nailed it, explaining regeneration simply while bringing an end to the Ninth Doctor's journey of self-forgiveness

2. Peter Davison as the Fifth Doctor in "The Caves of Androzani" For many hardcore Whovians, 1984's "The Caves of Androzani" is the greatest "Who" episode ever made. After The Doctor's curiosity lands him on a planet full of back-stabbers and scoundrels, he barely manages to escape with his companion, Peri. Both are poisoned, but he gives the antidote to Peri, leading to a dramatic regeneration where the Fifth Doctor sees visions of all his friends... and a taunting Master.

1. Matt Smith as the 11th Doctor in "The Time of the Doctor" We had a hard time deciding whether to put this or "Androzani" in the top spot, but Smith's farewell speech was the clincher. With Murray Gold's beautiful score in the background, The 11th Doctor connects regeneration to the human experience while saying goodbye to both Clara and the fans, all before Amy Pond returns to give her Raggedy Man one last goodbye.