: Tegan Jovanka (Janet Fielding) and Ace (Sophie Aldred) take center stage, helping UNIT's Kate Stewart defend Earth.
: 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. Doctor.Who.2005.S00E161.The.Power.of.the.Doctor...
: In a psychic liminal space, the Thirteenth Doctor meets versions of her former selves, including the First, Fifth, Sixth, Seventh, and Eighth Doctors . : Tegan Jovanka (Janet Fielding) and Ace (Sophie