Susan Foreman
From DoctorWho.com Wiki
Susan is the Doctor's Grandaughter. Sometimes called Susan Foreman, a name she took from the owner of the junkyard where the TARDIS was found parked at 76 Totters lane in the first episode An Unearthly Child. While the first Doctor was on business with the hand of Omega she enrolled in Coal Hill School where she was taught by Ian Chesterton and Barbara Wright who would join the Doctor on his Journeys.
In 2164 A.D. Susan fell in love with David Campbell during the Daleks invasion of earth where she parted ways with her Grandfather the Doctor.