According to producer John Nathan-Turner, when he was thinking of a name for the character, it was either going to be Tegan, after a friend's niece in Australia, or Jovanka, after Jovanka Broz, the widow of Yugoslavian President Josip Broz Tito, so he wrote both down on a piece of paper. Script editor Christopher H. Bidmead mistakenly believed that Jovanka was the character's last name rather than an alternative, and so christened her Tegan Jovanka.
Tegan is stubborn, loud, and direct, with a no-nonsense manner and not afraid to speak her mind (in Earthshock she describes herself as "just a mouth on legs"). Her time in the TARDIS coincides with that of Adric, Nyssa, Turlough and Kamelion. While she often bickers with them as well as with the Doctor, her strength of character keeps them together and her loyalty to her fellow crewmates is unquestionable. She is close to Nyssa, and is especially saddened at her leaving. The Doctor notes that she is a good coordinator, and often encourages her with the words, "Brave heart, Tegan." She is apparently able to speak one of many Indigenous Australian languages fluently, and shows an ability to use firearms.
Despite her strong front, however, her adventures with the Doctor, both thrilling and terrifying, eventually take a psychological toll. She is deeply upset by the death of Adric in Earthshock. After being left behind in Heathrow due to a misunderstanding at the end of Time-Flight she returns to the TARDIS in the subsequent adventure Arc of Infinity. Soon after she is once again possessed by the alien intelligence known as the Mara. Nyssa's departure affects her as well, and she is initially suspicious of Turlough's intentions in joining the Doctor. Eventually, the carnage surrounding the events of Resurrection of the Daleks prove too much and she bids an emotional good-bye to the Doctor and Turlough in 1984 London.
Tegan is mentioned in the new series in the 2007 Children in Need special episode "Time Crash" by the Tenth Doctor
Tegan's life after journeying with the Doctor is investigated in the Big Finish Productions 2006 audio drama The Gathering. Although she finds it difficult to enter into relationships and is suffering from a terminal illness, she tells the Doctor that she has no regrets about her time with him, and now appreciates her life to the full.
The spin-off fiction suggests that she was briefly married to pop star Johnny Chester (also known as Johnny Chess), the son of the First Doctor's companions Ian Chesterton and Barbara Wright. In the spin-off short story "Good Companions" by Peter Anghelides Tegan has suffered a nervous breakdown and convinced herself that her time with the Doctor was a delusion.