Sara Kingdom (played by Jean Marsh who later appeared in Battlefield and was the evil queen in the movie Willow) was sort-of a companion (probably best described as a potential companion) to the First Doctor in the story The Daleks' Master Plan.
In between those wacky adventures Sara also became a house, went to Seaworld and cried about her brother inside a giant clock. Eventually the poor sod listening to her go on and on about these totally canon stories decided to ring up one of the Doctors and made him pick her up again. She died again shortly later of a cold.
Jean Marsh was married to The Pertwurst from 1955 until their divorce in 1960.