Why Did David Tennant Leave ‘Doctor Who’? The Actor Is Returning to the Iconic TV Show

David Tennant and Donna Noble are back to reprise their roles for the "Doctor Who" 60th-anniversary special. Here's a glimpse of why the star left.

David Tennant and Catherine Tate are returning to the hit sci-fi series "Doctor Who" and are already filming for the show's 60th-anniversary special, to debut in 2023.

The pair will reprise their roles as the 10th Doctor on the drama from 2005 to 2010 and Donna Noble, respectively.

News about their return came after BBC announced the next Doctor, Ncuti Gatwa, from the hit Netflix series "Sex Education."

Previously, the Doctor and Donna separated when he erased her memories, himself included, as a life-saving measure. However, should she remember anything, Donna would die. Showrunner Russell T. Davies said:

“Maybe this is a missing story, or a parallel world, or a dream, or a trick, or a flashback. The only thing I can confirm is that it's going to be spectacular, as two of our greatest stars reunite for the battle of a lifetime.”

WHEN DID DAVID TENNANT LEAVE "DOCTOR WHO?"

Tennant first joined the show in 2005 to be the 10th Time Lord with his three companions: Rose (Billie Piper), Martha (Freema Agyeman), and Donna.

However, he announced his exit in 2008, leaving fans disappointed over his departure. Despite his revelation, Tennant continued to play the Doctor in four 2009 specials before a new Doctor took over. His curtain call was on New Year's Day 2010.

In 2013, fans were shocked to see Tennant appear for the award-winning show's 50th-anniversary special, "The Day of the Doctor."

WHY DID TENNANT LEAVE "DOCTOR WHO?"

Tennant is undoubtedly proud to be part of the show and felt "very privileged to have been part of this incredible phenomenon." With his departure, the actor said:

“I'd always thought the time to leave would be in conjunction with Russell T. Davies and Julie Gardner, who have been such a huge part of it all for me.”

Writer Steven Moffat revealed that Tennant was actually tempted to stay after hearing his pitch for season 5. "David was just going through the – now, to me, very familiar – angst about leaving," he said. "I went to talk to David, and I ran him through what the series would be if it was him."

After much thinking, Tennant decided to decline Moffat's offer and leave the show, bringing in a new star to play the lead role.

STEVEN MOFFAT HAD AN IDEA IF DAVID TENNANT STAYED IN "DOCTOR WHO"

Should he have stayed, Moffat's vision of the series would have been the Doctor crashing into a back garden to regenerate while Amelia helped him. Amelia would later meet him again as an adult, but he would not recall that memory.

"We come to realize that was the Doctor from the future – we'd make our way through the series to the point where the Doctor gets back to that," Moffat said.