Pauline Collins
Pauline Collins, OBE played Samantha Briggs in The Faceless Ones and Queen Victoria in Tooth and Claw.
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 holds the record for the most amount of time between appearances on Doctor Who, narrowly edging Margaret John.
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.