Pauline Collins
Pauline Collins, OBE played Samantha Briggs in The Faceless Ones and Queen Victoria in Tooth and Claw. Her image would be used for a painting of Queen Victoria in Empress of Mars.
She was heavily solicited to convert Samantha into a regular companion to replace Polly. Despite personal appeals by Innes Lloyd and even Frazer Hines, however, she declined the offer.
According to David Tennant on the DVD commentary for The Idiot's Lantern, she held the record for the most amount of time between appearances on Doctor Who, narrowly edging Margaret John. This has since been eclipsed by Ysanne Churchman, whose reppearance as Alpha Centauri in Empress of Mars came 43 years after her last, in 1974's Planet of the Spiders, as the voice of one of the Eight Legs.
She is one of the few Oscar-nominated actresses to appear in Doctor Who.
As documentary subject
Collins' views on her time in The Faceless Ones, as well as her memories of being invited to become a companion, were a part of the audio documentary Doctor Who - The Lost Episodes.