Liz Shaw, portrayed by Caroline John, was a companion of the Third Doctor. She was a scientist and civilian member of UNIT.
She first appeared in Spearhead from Space, where she became a member of UNIT and met the newly regenerated Doctor. In Inferno Liz decided to leave the Doctor and UNIT, and go back to the University of Cambridge.
She helped repel the first Nestene invasion attempt, witnessed the reawakening of the Silurian creatures, helped to prevent the kidnap of three alien ambassadors and stopped an insane scientist from cracking open the Earth’s crust.
During this latter adventure the Doctor visited a fascist parallel universe, where Liz was known as Section Leader Shaw! After only a handful of adventures, Liz eventually returned to Cambridge to continue her research.