Tarkin

After attending the American premiere of the first Star Wars film in May 1977, the Sixth Doctor remarked that the actor who played Tarkin looked familiar, and seemed to recall meeting his granddaughter. (PROSE: Mission: Impractical)

Behind the scenes
Grand Moff Wilhuff Tarkin, Governor of the systems of the Outer Rim, was played by Peter Cushing, who also played Dr. Who in Dr. Who and the Daleks and Daleks' Invasion Earth 2150 A.D., two theatrical adaptations of The Daleks and The Dalek Invasion of Earth, respectively. The granddaughter in question is Susan.