- You may be looking for Barbara Wright.
Barbara was not very good at mathematics at school, with her last school report stating that she would probably make a good housewife someday but little else. (NOTVALID: Doctor Who 3 - The Third Motion Picture)
She accompanied Dr. Who on his first trip to the planet Skaro in Tardis, which her grandfather had invented. During her travels, she met the Daleks and then an ancient Roman legion in 64 AD. (NOTVALID: Dr. Who and the Daleks, Dr Who and the House on Oldark Moor)
They subsequently travelled to Oldark Moor and met Count Tarkin, (NOTVALID: Dr Who and the House on Oldark Moor) but Barbara was absent during two of Dr. Who and Susan's subsequent adventures, as was Ian, (NOTVALID: Daleks' Invasion Earth 2150 A.D., Daleks Versus the Martians) whom Susan believed that she eventually stopped seeing, though she had not actually gotten over him.
Partway through the Scriptwriter's typing the script of the third Dr. Who film which would have featured Barbara rekindling her relationship with an increasingly, literally clownish Ian, Susan realised that she and all her family were fictional constructs; she reached out into the real world and killed the Scriptwriter by staking him through the heart, putting an end to the franchise and freeing herself from fictionality. (NOTVALID: Doctor Who 3 - The Third Motion Picture)
Behind the scenes
Susan is revealed to be Dr. Who's great-grandmother in Doctor Who? 106 due to the fact that Time Lords get younger with each regeneration. This visibly shocked Dr. Who, apparently having been unaware of his true lineage. However, Barbara, his other supposed granddaughter, is not mentioned in the story so her real relationship to Dr. Who remains unclear.