Doctor.who.2005.s00e161.the.power.of.the.doctor... -

: Tegan Jovanka (Janet Fielding) and Ace (Sophie Aldred) take center stage, helping UNIT's Kate Stewart defend Earth.

: While the Master manipulates the Doctor’s timeline, the Daleks attempt to trigger volcanic eruptions across Earth, and a Cyberman-controlled planet threatens the globe.

: Reflecting her playful and optimistic nature, Whittaker’s final line is a simple: "Right then, Doctor whoever-I'm-about-to-be... tag, you're it" . Doctor.Who.2005.S00E161.The.Power.of.the.Doctor...

Farewell to the Thirteenth Doctor: A Look Back at "The Power of the Doctor"

True to its status as a centenary special, the episode is packed with : : Tegan Jovanka (Janet Fielding) and Ace (Sophie

: The episode concludes with a "companion support group" featuring surprise appearances from Ian Chesterton (William Russell), Mel Bush (Bonnie Langford), and Jo Grant (Katy Manning). The End of an Era

"The Power of the Doctor" is more than just a goodbye; it is a celebration of the Doctor's true power: the ability to inspire, to build a "fam," and to face the future with open arms. tag, you're it"

: In a first for the series, the Doctor regenerates back into a familiar face— David Tennant , returning as the Fourteenth Doctor —setting the stage for the 60th-anniversary specials.