Gavin (The Empty Planet)

Gavin was a half-Human and heir to the throne of a planet half way across the universe.

Biography
Gavin's father was the king of an unnamed planet who had travelled to Earth for an unknown reason, and reproduced with a Human woman, producing Gavin. Unwilling to have his people come looking for his son, Gavin's father gave his mother a bio damper to give to the boy, prior to his returning home. The bio damper prevented Gavin from being discovered, masking his alien biology. Gavin's mother later died, and he was sent to live with his aunt and uncle, who cared little for him.

Due to his half-alien status, Gavin was left on the Earth when the Automatons of his homeworld, searching for him following the death of his father, used Warp shunt technology to remove all Humans and Mr. Smith from it, except for Clyde and Rani, who had been grounded by the Judoon.

Clyde and Rani then helped Gavin discover who he really was. He ordered the return of the Humans and proclaimed Rani and Clyde lords. After she returned to Earth, Sarah Jane had Mr Smith edit records to say that Gavin had gone to live with relatives in Australia. (SJA: The Empty Planet)