Leela (Louise Jameson)
The rebellious Leela was a member of the warrior Sevateem tribe. She had just been exiled for heresy when she met the Doctor, who closely resembled the tribe's god, Xoanon.
Leela forced her way into the TARDIS, and quickly became a loyal ally, who was usually quite capable of looking after herself, (although the Doctor strongly disapproved of her use of poisonous Janus thorns).
During her travels Leela struggled with concepts and technology beyond her comprehension, but was inquisitive and keen to learn. After the Sontarans' attempt to invade the Doctor's home planet, Leela decided to remain there with Commander Andred.