Sarah Jane Smith
Sarah Jane was a regular companion of the Third and Fourth Doctor, on the programme from 1973 to 1976 (seasons 11 – 14). She returns in the Fifth Doctor story "The Five Doctors" (1983), the 30th anniversary story Dimensions In Time (1993), and most recently in the  episodes "School Reunion" (2006), and "The Stolen Earth"/"Journey's End" (2008), alongside the Tenth Doctor, and other companions of his era. The Tenth Doctor also featured in her own TV series "The Sarah Jane Adventures".