David Campbell

David Campbell was a freedom fighter fighting on Earth during the Daleks' invasion and occupation of Earth (2157 - 2167). He encountered Susan when she and the Doctor, Ian Chesterton and Barbara Wright landed in London.

With his help they stopped the destruction of London and helped destroy the Daleks. He and Susan quickly fell in love, she stayed with him to help restore the Earth. (DW: The Dalek Invasion of Earth)

David and Susan spent at least 30 years together; however by the time that David was 54, Susan still looked 18, due to her Time Lord physiology. (EDA: Legacy of the Daleks)

A conflicting account of Legacy of the Daleks states that David was the father of Susan's child Alex and died soon after his birth for unknown reasons. David was heralded as a great Earth hero for his efforts during the invasion. (BFA: An Earthly Child)