Sarah Jane Smith is a companion of the Third and Fourth Doctors, having also met the Tenth and Eleventh incarnations. A journalist, Sarah Jane meets the Doctor whilst trying to infiltrate a UNIT-controlled facility to find out more about some scientists that have gone missing. Sarah Jane accidentally stows away in the TARDIS when the Doctor travels back in time, staying with him as a companion afterwards. Due to the Doctor’s association with UNIT, Sarah Jane also becomes friends with a few of its members, such as the Brigadier, Mike Yates and Harry Sullivan. When the Doctor is summoned back to Gallifrey, he leaves Sarah Jane back on Earth. Later in her life, Sarah Jane becomes one of the most important journalists in the UK and never stops chasing alien threats and fighting them off; creating a Xylok-based supercomputer she named Mr Smith to help her with data collecting and analysis. She also has two adopted children of alien origin, Luke and Sky.