Katrina Moorkroft was an ancient, evil succubus who retained her youth and beauty by sucking the lifeforce from male victims. Over the years she also became incredibly wealthy, explaining her fortune away as inheritance. Katrina moved to Megakat City and using her money to build several parks and libraries, as well as founding the Moorkroft Philharmonic Hall as a center of culture for the city, acts which made her a darling of the money-hungry Mayor Manx, who did everything he could to keep her happy.
She was assisted in her endeavors by three loyal servants, including chauffeur Otto and butler Laszlo, who also benefited from absorbing the lifeforce of their employer's victims. They would routinely go out and abduct victims for her, taking them back to her mansion, Moorkroft Manor, where Katrina drained them in her observatory. In this manner, she was responsible for the deaths of six innocent kats. However, draining their lifeforces only temporarily restored her youth, and if she went too long between feedings, she would age drastically into the elderly woman she really was. She needed to absorb the lifeforce of someone who loved her during an eclipse on a centennial event. If she did this, her beauty would last for a hundred years before she needed to kill anyone again.
She found her chosen victim in Commander Feral, who she was introduced to through Mayor Manx. Either by choice or because of Katrina's malicious charm, Feral fell hopelessly in love with the wealthy Moorkroft "heiress," and she slowly drained his lifeforce over the course of several days. Suspicious because Katrina's arrival coincided with the gruesome deaths plaguing Megakat City, Felina Feral and Callie Briggs sought the assistance of Dr. Abby Sinian. Otto followed them, and when he discovered that Sinian knew too much, and that now, so did Feral's niece and the Deputy Mayor, he released his employer's pet ferret into the museum, which transformed into a ferocious, three-headed beast. However, its attempt to kill the three was thwarted by the SWAT Kats, who defeated the monster using a Mega-Octopus Missile.
Despite her pet's failure and Otto's warnings that her chosen victim's niece knew too much, Katrina insisted on going ahead with her scheme, assuring Otto that it didn't matter how much Felina knew because everything would be over the next night. While she and Feral ate dinner in Moorkroft Manor, Katrina set a trap for Felina, who she knew would be spying on them, sending Otto and Laszlo to dispose of the dead body of her latest victim, the Skycor Towers foreman. The two captured her and brought her back to the mansion. When Feral asked Katrina to marry him, unaware of his niece's predicament, Katrina held off answering and took him to the mansion's observatory to witness the eclipse. There, she began to drain him, while Otto brought a tied up Felina in to watch. However, Felina managed to use a beeper given to her by T-Bone to call the SWAT Kats for assistance. The vigilantes arrived in their Delta-Bak Paks and battled against Katrina's pet ferret, which turned into its three-headed monster form, and her servants, who turned into gargoyles. The SWAT Kats, with Felina's help, defeated them all.
Katrina, transforming into her true, monstrous form, grabbed a by now drastically aged and unconscious Feral and flew away with him. Following in the Turbokat, the SWAT Kats battled her in the air. Using boomerangs fired from the jet, Razor made Katrina drop Feral, whose descent was halted using an Airbag Missile. The eclipse ended, and Katrina, having failed to fully drain her victim, died as she aged into dust.
- Katrina appears in the unfinished season two episode "Succubus!", also known as "The Curse of Kataluna". Although the episode never aired because it was never finished, the script exists in its complete form.
- Her basic character (as well as the plot) was recycled for the Jonny Quest episode "Eclipse", where she was renamed Elise Lenoir, and in Scooby-Doo on Zombie Island, where she was named Simone Lenoir.