Jenna Stannis, described by Servalan as a "superior grade citizen of the Federation", was one of Roj Blake's followers and served in the capacity as the Flight Officer of the Liberator and (along with Kerr Avon) was effectively one of Blake's "lieutenants" during his command of the ship prior to the Intergalactic War.
Jenna's mother was violently assaulted by a squad of Federation troopers sometime prior to Jenna meeting Blake.
Just prior to her arrest, she was an experienced smuggler, or as she would later euphemistically say a "free trader". In course of her "trading" she worked with revolutionaries such as Avalon and space pirates like the Amagons.
Just before her arrest she was in discussions with Largo, an up-and-comming member of the Terra Nostra, to haul a cargo between Jupiter's moon Callisto and Earth. She discovered that the cargo was Shadow, a highly illicit and potent narcotic. Personally opposed to the use of that drug, she turned him down. Immediately afterwards she was arrested.
Top Ace of the Seven
Jenna first met Blake in the holding cell awaiting transportation to Cygnus Alpha. While initially cold to Blake, her mood softened after his lawyer visited him with information confirming much of his story. The visit gave her some hope for herself as well, but the schedule for the London's departure was pushed forward before Blake would have been able to capitalize on the revelation. (A: The Way Back)
On board the prison ship, she joined Blake in attempting to take it during a large naval engagement the ship had inadvertently gotten in range of, and was able to make it to the computer room with Blake and Avon. After Blake surrendered, she was fully restrained along with Avon and Blake, but was released on them to explore the drifting Liberator soon afterwards. Along with Avon, she inadvertently saved Blake's life after deducing the controls well enough to pilot the warship away from the London after Avon closed the exterior hatch. (A: Space Fall)
After distancing themselves from the prison ship, they began to explore the ship's systems more throughly. When she tried to manipulate one control the vessel began to scan her mind. It was this telepathic communication that enabled the use of Zen for the crew, and also provided the name of the Liberator, which Zen claimed he took from her mind. Soon afterwards she argued and then forced Avon to teleport Blake back from the surface of the prison planet in his attempt to save the prisoners from the London. (A: Cygnus Alpha)
Jenna quickly mastered the manual controls of the Liberator and would take direct control whenever a dangerous situation arose, from combat with pursuit ships to meteor showers. (A: The Web) She also occasionally accompanied Blake on the ground, and where she proved to be a capable survivor (although she was occasionally overwhelmed when caught unprepared). (A: Duel)
One of her last acts aboard the Liberator was to alert the Federation, more directly Servalan, to the incoming alien invasion force approaching from the Andromeda galaxy (over Vila's protests). This proved the decisive factor in the victory of the Milky Way forces over the invaders in the Intergalactic War, as it allowed the combined Federation military to rendezvous with Liberator at Star One.
She remained with an injured Blake when the ship had to be abandoned during the Intergalactic War. On Sarran, Avon was told by Zen that she was on a hospital ship with superficial injuries, and soon afterwards was further informed was that she had left the hospital ship and was on a cargo ship headed to Morphenniel.
Jenna's activities beyond that point are unknown. Blake later claimed, when talking to Tarrant, to have learned how to use a random flight program from her, but does not state where or when and so it could have been something that happened on the Liberator. He also claimed that she had committed suicide by self-destructing her ship while trying to run a blockade, destroying "half a squadron of gunships" at the same time.