Kate Stewart

Kate Stewart, born Kate Lethbridge-Stewart and nicknamed by her father "Tiger", was the daughter of Alistair Gordon Lethbridge-Stewart and his first wife, Fiona. (PROSE: The Scales of Injustice)

Biography
Kate was five at the time of the Wenley Moor Silurian incident. (PROSE: The Scales of Injustice)

Kate was the mother of Gordon Lethbridge-Stewart. She ended up estranged from her father, though they re-united circa 1997. (HOMEVID: Downtime)

In 2004, Kate encountered Mastho, one of the last Daemons. (HOMEVID: Dæmos Rising)

Later, Kate had dropped the name "Lethbridge" when she became the head of scientific research to UNIT so as to avoid favours. (TV:  The Power of Three)

Behind the scenes
Kate Stewart is the first character created for a direct-to-video Doctor Who spin-off to be reintroduced in the television series itself.