This page contains information regarding Star Trek: Picard, and thus may contain spoilers.
In the 2380s, Clancy supported a firm stance of the Federation towards the Romulan Star Empire in the face of the looming threat of the Romulan supernova. Even before the attack on Mars in 2385, she was concerned about the potential secession of Federation member worlds over the continued Starfleet support of Romulan evacuation efforts, spearheaded by Admiral Jean-Luc Picard. (PIC: "Maps and Legends")
In 2399, Clancy served as CNC of Starfleet. In that year she was approached by Picard in her office in San Francisco, who requested a reactivation of his commission to investigate the death of Dahj Asha. Although Clancy soundly denied his request, she still later prompted Commodore Oh with an investigation of Picard's claims about a Romulan infiltration of Starfleet. (PIC: "Maps and Legends")
Picard and Clancy did not always see eye-to-eye. Clancy was especially angered by Picard's denouncement of Starfleet and his eventual public resignation following the agency's decision against further support of the Romulan cause in 2385. She also expressed concern that Picard may no longer stay out of the public eye following his blunt interview with FNN in 2399. Despite her resentment of Picard, Clancy still took his concerns serious enough to start a quiet investigations of his claims. (PIC: "Maps and Legends")
Clancy seemed to have a trusting working relationship with Commodore Oh. Following Picard's reports of a possible Romulan plot against the Federation, Clancy sought Oh's advice on the matter, not realizing the Commodore's own involvement with the Zhat Vash. (PIC: "Maps and Legends")
"The Romulans were our enemies, and we tried to help them for as long as we could, but even before the synthetics attacked Mars, fourteen species within the Federation said 'Cut the Romulans loose, or we'll pull out.' It was a choice between allowing the Federation to implode, or letting the Romulans go."
"The Federation does not get to decide if a species lives or dies."
"Yes we do. We absolutely do. Thousands of other species depend upon us for unity, for cohesion. We didn't have enough ships left. We had to make choices, but the great Captain Picard didn't like his orders."
"I was standing up for the Federation for what it represents! For what it should STILL represent!"
"How dare you lecture me!"
"This is no longer your house, Jean-Luc, so do what you're good at: go home. Request denied."
Kirsten Clancy was played by Ann Magnuson. Clancy is seen wearing a five pip admiral's rank, the first time such an insignia has ever been seen on screen. She is the first "prime reality" Starfleet fleet admiral seen on camera since Fleet Admiral Cartwright appeared in Star Trek VI: The Undiscovered Country twenty nine years earlier.
Fleet admiral Marcus of the Kelvin timeline was depicted in Star Trek Into Darkness. A mirror universe fleet admiral (Fleet admiral Gardner) was depicted in In a Mirror, Darkly, Part II. Fleet admiral Shanthi, who appeared in TNG: "Redemption II", appears to have been a vice admiral holding the title of fleet admiral, possible due to the nature of her position.
The character also appears in The Last Best Hope, which is set before the series.