DOCTOR Who fans were surprised with a familiar face as Jodie Whittaker’s 13th Time Lord regenerated into David Tennant in the dramatic conclusion of the show’s BBC centenary special.

It was previously announced that Scottish actor Tennant, who first stepped into the Tardis in 2005 to play the 10th Doctor, would be returning to the sci-fi series for the show’s 60th anniversary celebrations – but it was not revealed in what capacity.

Following Sunday’s 90-minute special, the BBC confirmed Tennant will become the 14th incarnation with Catherine Tate reprising her role as his former companion Donna Noble for three special episodes set to air in November 2023.

READ MORE: David Tennant's five most memorable moments as Doctor Who

Ncuti Gatwa will then take control of the Tardis as the 15th Doctor, with his first episode due to air over the festive period in 2023.

Talking about the future, returning showrunner Russell T Davies, said: “If you thought the appearance of David Tennant was a shock, we’ve got plenty more surprises on the way.

“The path to Ncuti’s 15th Doctor is laden with mystery, horror, robots, puppets, danger and fun.

“And how is it connected to the return of the wonderful Donna Noble? How, what, why? We’re giving you a year to speculate, and then all hell lets loose.”

Fans were thrilled with the news, taking to Twitter to express their excitement.

One viewer wrote: "David Tennant has returned to Doctor Who and Boris Johnson has pulled out of the leadership contest. This might just be the best 10 minutes of my life."

Others said they were "lost for words" and "had chills" following the episode.

Whittaker’s last venture as the Doctor was loaded with drama as it saw her fight for her existence against some of her deadliest enemies: The Master, the Daleks and the Cybermen.

The episode, titled The Power Of The Doctor, also saw the surprise return of actors who have played Time Lords from the ages including Colin Baker, Peter Davison, Paul McGann and Sylvester McCoy.

READ MORE: Doctor Who star David Tennant ranked hardest-working actor

After the episode, a teaser trailer of the 60th anniversary special episodes aired which showed Tennant and Tate facing a deadly enemy played by Neil Patrick Harris and a brief glance at Gatwa’s 15th doctor.

Whittaker, 40, became the first woman to portray the Doctor when she took over the role from Peter Capaldi in 2017.

Showrunner Chris Chibnall is also set to leave the programme, to be replaced by Davies, who was behind the 2005 revival of the show.