Harry Sullivan (Ian Marter)
Surgeon Lieutenant Harry Sullivan was assigned by the Brigadier to look after the newly-regenerated Doctor, and soon accepted an invitation to enter the TARDIS.
Unflinchingly brave, if rather clumsy, Harry was of invaluable assistance during a brief series of adventures, which included a visit to Skaro to witness the creation of the Daleks and an encounter with the Cybermen.
Harry returned to Earth when the Doctor was summoned by the Brigadier to investigate a series of disappearing oil rigs, and decided to stay when the Zygon menace was thwarted. The Doctor and Sarah later encountered an android replica of Harry, created by the Kraals.