The niece knows too much.
Otto was one of Katrina Moorkroft’s servants, serving as her chauffeur. Like all of Katrina’s servants, Otto was capable of transforming into a hideous gargoyle, and would routinely abduct male victims and take them back to the mansion for their employer to drain. Evidently, they were granted prolonged life and youth the same as her. Otto drove Katrina to Enforcer Headquarters to and later the Moorkroft Philharmonic Hall for her date with Commander Feral. After the performance, when Katrina began to rapidly age after having gone too long between feedings, Otto drove her home to Moorkroft Manor, where she drained the life of a Skycor Towers construction foreman captured by Laszlo.
When Feral’s niece Felina and Callie Briggs sought the help of Dr. Abby Sinian, Otto, with his employer’s pet ferret in tow, followed them to the Megakat City Museum of History, posing as part of a tour group. He released the ferret into the museum, where it turned into a three-headed monster and tried to kill the three women. After the beast was defeated by the Swat Kats, Otto retrieved it after it reverted to its normal form, and reported back to Katrina. Later, he and Laszlo were part of a trap set by their employer to capture Felina. Knowing her boyfriend and future victim’s niece would be spying on Moorkroft Manor, she ordered Otto and Laszlo to take the body of the Skycor Towers foreman and dump it in Megakat Marsh, knowing Felina would follow them. When she did, he and Laszlo captured her.
Otto was later present when Katrina attempted to drain Commander Feral during an eclipse. When the Swat Kats intervened, freeing Felina, he, Laszlo and a third servant turned into the gargoyle forms and fought the vigilantes and the Enforcer lieutenant. Razor tied up Otto’s wings with a Bola Missile and knocked him out a hole in the wall, but he recovered. He battled Felina, who defeated him. When Katrina died, Otto, like all of her other servants, aged into dust.
Otto appears in the unfinished season two episode Succubus!, also known as The Curse of Kataluna. He is described as resembling Austrian actor Erich von Stroheim, who played the chauffeur Max in the classic film Sunset Blvd.
Although the episode never aired because it was never finished, the script exists in its complete form. As a result, however, we have no idea of who Otto’s voice actor would’ve been (only Nancy Linari as Katrina has been confirmed).
His basic character (as well as the plot) was recycled for the Jonny Quest episode Eclipse, where he and the other servants were combined into a single character, Andrew.