Fans of the long-running, much-beloved British sci-fi show Doctor Who likely have a favorite incarnation of the titular role. For many, especially those who started watching with the 2005 revival, that favorite is David Tennant.

Tennant joined the program as the Tenth Doctor only a year after the show returned to the screen, and his bright personality and three-season tenure made his portrayal of the Doctor one of the most memorable. Tennant's departure from Doctor Who marked the end of era, even if it was amicable.

David Tennant's Tenth Doctor was a fast-talking, energetic character, brining a liveliness to the role that helped cement this incarnation as a fan-favorite. His iconic Chuck Taylors and blue suit offered a shift from the Ninth Doctor's leather jacket, and his fun personality kept viewers entertained even when he was tackling serious issues.

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Doctor Who Tennant fire

Tennant took over the role from Christopher Eccleston, the Ninth Doctor and the actor responsible for revitalizing the character when Doctor Who returned to the screen. Eccleston left after just one season, and the two shared the role in the episode "The Parting of the Ways" as the Doctor regenerated into his new, Tennant form. Tennant stayed on as the Doctor for three seasons, becoming the iconic representation of the role for newer audiences.

In 2008, Tennant announced he would be relinquishing the role of Doctor. While the last Doctor left the role on uneasy terms with the showrunners, it seemed Tennant was leaving on his own terms. He wanted to leave the role before the magic ran out and while people still wanted more, ensuring his character wouldn't grow stale and that the Tenth Doctor could bow out at the height of his popularity. This tactic of ending before outstaying their welcome has worked successfully for a number of shows, and based on the popularity of Tennant's Doctor, it worked for him too.

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Tennant's timing had the added benefit of providing a clean break for Doctor Who. The showrunner of the first four seasons, Russel T. Davies, was stepping down as well, handing off the torch to Steven Moffat. Davies and Moffat worked together on the series of specials that aired between 2009 and 2010, including the transition from Tennant to the Eleventh Doctor, Matt Smith, in "The End of Time." The departure of both Davies and Tennant allowed for the new cast and crew to make large scale changes more easily.

While David Tennant's departure from Doctor Who marked the end of an era, it also provided the show with a concrete divide as it moved in a different direction. Tennant left the show still in love with the part and the stories they told, and made a point of wanting to leave before Doctor Who ever felt truly like a job. Tennant has since gone on to other roles and continued his robust career, but his most memorable character will always be the Tenth Doctor.

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