Katarina is a fictional character played by Adrienne Hill in the long-running British science fiction television series Doctor Who. An inhabitant of ancient Troy, she was a companion of the First Doctor and appeared in the programme from November to December, 1965.

Katarina was introduced in the serial The Myth Makers , which took place during the siege of Troy. She was a handmaiden of the prophetess Cassandra, and helped the TARDIS crew survive the events of the siege. When Steven was wounded, she helped him into the TARDIS as Vicki decided to stay behind in Troy with the warrior Troilius.

A sweet, simple young woman who could not really cope with the concept that the universe was suddenly opened up to her, Katarina believed that she was dead, and that the Doctor was a god that was transporting her to the next life. She referred to the TARDIS as a "temple", and literally worshipped the Doctor, referring to him as "Lord" (much to his annoyance) and having absolute faith in him.

During The Daleks' Master Plan, Katarina was taken hostage by an escaped prisoner called Kirksen, who demanded that the Doctor take him to Kembel, a planet taken over by the Daleks. To prevent the Doctor from giving in to Kirksen's demands, she triggered the controls to the airlock she was being held in, propelling both her and her captor into the vacuum of space.

Despite her brief tenure on the series, Katarina is significant for being the first of the Doctor's companions to die on-screen. However, she would not be the last. Her death, and later that of Adric, has always weighed heavily on the Doctor's mind. Katarina also appeared in the spin-off short story Katarina in the Underworld by Steve Lyons, describing the efforts of Katarina's spirit to pass into Elysium.

• Travelled from: The Myth Makers to The Daleks' Master Plan