A third incarnation of Romana has been depicted in some of the spin-off novels, and a fourth (performed by Juliet Landau) has been featured in several audio dramas released by Big Finish Productions in 2013 and 2014, and appeared again in early 2015.

The White Guardian originally assigns Romana to assist the Doctor during the quest for the Key to Time, a series of linked serials which constitute the whole of Season 16 (1978–79).

Over the course of Season 16, Romana begins to take on some of the characteristics of the screaming "damsel in distress", which reinforced Tamm's decision not to remain in the role as she felt the character had been taken as far as she could go.

The introduction of Romana's second incarnation at the start of Destiny of the Daleks — a script credited to Terry Nation, but with several additions and alterations by script editor Douglas Adams — treats the concept of regeneration humorously;[7] Romana changes bodily forms several times, rather like someone casually trying on different outfits, before deciding to take the form of Princess Astra, who had been played by Lalla Ward in the final serial of Season 16, The Armageddon Factor.

The opening of the next serial Full Circle makes it clear that, having travelled with the Doctor, she no longer desires to return home.

Her final television appearance was in the 1981 story Warriors' Gate where, along with the robot dog K9, she leaves to forge her own path in E-space when faced with a choice of remaining there or returning to Gallifrey.

Outside of the television programme, the Fourth Doctor and Romana II also appear in Australian-filmed television advertisements for PR1ME Computer, Inc. in 1980, which played in a tongue-in-cheek way with the idea that the two characters shared a romantic relationship, climaxing with the Doctor proposing marriage (which occurred in real life between Tom Baker and Lalla Ward after her departure from the series that same year).

In the licensed Virgin New Adventures novel Blood Harvest by Terrance Dicks, Romana II leaves E-Space and returns to Gallifrey with the help of the Seventh Doctor.

In Goth Opera by Paul Cornell, from the complementary Missing Adventures series, she is given a seat on the High Council of Time Lords.

With the Doctor refusing to allow the Time Lords to make Compassion a slave, he, Compassion and fellow companion Fitz Kreiner go on the run between The Shadows of Avalon and The Ancestor Cell, the final confrontation on board the Doctor's believed-destroyed original TARDIS resulting in the obliteration of Gallifrey and the apparent retroactive wiping out of the Time Lords from history.

In the story, it is revealed that Romana II was abducted by the Daleks soon after assuming the presidential office, and remained in captivity for twenty years before making her escape, briefly reuniting with the Doctor before reassuming her post.

Complicating this is the escape of an ancient evil called Pandora from the Matrix in the paradoxical form of Romana's first incarnation (played once again by Mary Tamm).

With Gallifrey on the brink of economic and social collapse, as well as in danger of being overrun by a Free Time virus, Romana and her friends flee through several alternate universes.

Big Finish's spin-off line The Companion Chronicles has featured new performances by both Ward and Tamm in a number of stories set within their respective continuities.

To avoid confusion with her earlier self, this future Romana volunteers to use the name Lady Trey (taken from one of the middle syllables of her full name)[citation needed].

This story is revealed in the follow-up Enemy Lines to depict what happens shortly after Ward's incarnation is forced to regenerate and sees Gallifrey on the brink of another war.

As well as Gallifrey Romana II also featured in a series set while travelling with the Doctor and Adric in E-Space, the Lost Story The Doomsday Contract, and The Eighth of March 2: Protectors of Time.