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, and had to make herself look older. (EDA: Legacy of the Daleks)

Legacy of the Daleks also states that David was the father of Susan's child, Alex, and died soon after his birth for unknown reasons. It also states that they adopted three orphaned children, who they named, David Campbell Junior, Ian Campbell and Barbara Campbell, after Susan's former teachers and her husband. David was heralded as a great Earth hero for his efforts during the invasion. (BFA: An Earthly Child)