Alex Campbell

Alexander David Campbell was the son of Susan Foreman and the great-grandson of the Doctor.

Early life
Alex was the only biological child of Susan and David Campbell. He was born ten years after the end of the 22nd century Dalek occupation of Earth. Susan and David did not tell him about his true heritage, as they believed it would make it hard for him to live his life on Earth. (AUDIO: An Earthly Child)

Meeting the Doctor
After his father's death, Alex grew rebellious. He joined youth groups opposed to the new Earth Council. In the 2190s, when he was seventeen, he met his great-grandfather for the first time, who saved him from the Guldreasi and told him of his origins. The Doctor wanted Alex to have an education on Gallifrey so that he could fulfil his full academic potential as a Time Lord. However, Alex saw Earth as his home and decided to stay with his mother. (AUDIO: An Earthly Child)

Six months later, Alex had Christmas dinner in the TARDIS with his mother, the Doctor and Lucie Miller. Although the Doctor was his great-grandfather, he came to refer to him simply as "Granddad." During this visit, the Doctor analysed Alex's DNA and discovered that Gallifreyan genes constituted only 7% of his genome. Unlike full blooded Time Lords, he was not telepathic and could not regenerate. The Doctor intended to give the TARDIS to Alex at some point, though only after he had travelled with him, even arranging a room for him. However, Alex decided to go on a grand tour of Europe with Lucie instead. (AUDIO: Relative Dimensions)

Fighting the Daleks and death
During the Daleks' second attempt to conquer Earth, Alex fronted a resistance with Lucie and saved the Doctor from being blown up in a Dalek saucer. Alex and Lucie travelled in a Dalek saucer to the Dalek base in North America with a bomb to destroy them. The saucer was caught in a magna-clamp, and Alex and Susan were taken from the saucer. However, he ran at the clamp's control panel and was shot by a Dalek, destroying the controls but killing Alex. (AUDIO: Lucie Miller / To the Death)

Physiology
Unlike his mother, as a Gallifreyan/human hybrid, Alex Campbell had one heart. (AUDIO: An Earthly Child) He had 7% Gallifreyan gene. (AUDIO: Relative Dimensions)