Rodan

Rodan was a Time Lady who worked as a controller on Gallifrey. She helped to fight invasions of her homeworld by first the Vardans and then the Sontarans. (TV: The Invasion of Time)

As a very junior Time Lord, Rodan was assigned monitor duty. A technician reported to her the arrival of a stolen TT capsule on Tersurus, and she reported it to the Castellan. (PROSE: Legacy of the Daleks)

Rodan later worked on maintaining the protective transduction barrier around the planet, monitoring threats to Gallifrey and reporting on it to her superiors.

Rodan befriended Leela, recently abandoned by the Fourth Doctor (who was pretending to collaborate with the invading Vardans). Both women were exiled by the Doctor outside the Capitol as part of his ploy so they could gather resistance to fight off the invaders. Rodan found a natural environment hard to cope with mentally. After the Doctor had K9 disable the transduction barrier and Gallifrey was invaded by the Vardans and the Sontarans, she worked to restore it. (TV: The Invasion of Time)

Behind the scenes
Other than Susan Foreman, Rodan was the first female Gallifreyan seen on screen. Another Time Lord, Romana I, joined the the Fourth Doctor in his travels in the following season.