Karl Kyle, brother of Selina Kyle, is inspired by his sister's infamy to become a costumed criminal. His catlike garb and his crimes revolve around a theme of cats, and he resembles a male version of Catwoman.
In March 1952, Gotham City was struck by a series of feline-related crimes, perpetrated not by the now-reformed Selina Kyle, but by a costumed criminal known as The King of Cats, a cunning mastermind whose theme revolves around cats. The King of Cats sends flowers to Kyle, causing Batman to investigate her involvement. He soon becomes convinced that she is innocent, but asks that her, the expert on feline-themed crimes, to aid him and Robin in arresting the King of Cats. Selina, however, refuses, much to Batman's surprise, and he comes to the conclusion that Miss Kyle has fallen in love with the costumed arch-criminal. Selina had refused, in fact, because she had realized the King of Cats was her brother, Karl, and thus refuses to aid in his capture. Batman and Robin raid Selina's pet store shortly afterward, catching the King of Cats attempting to lure Selina out of her retirement and back into a life of crime. The King of Cats is easily captured by Batman and Robin, but Selina Kyle pleads with Batman to let him go. When he refuses, she knocks him out and allows her brother to escape. Selina asks her brother to end his criminal career and turn himself in, and he promises to consider the offer. Shortly after, Batman attacks the King of Cats at the zoo and in the following battle, both are thrown into separate tiger pens, each trapped without one being able to aid the other. Catwoman, in her old costume, arrives and saves both from certain doom. The King of Cats is remorseful over his crimes, and he promises to abandon his criminal ways and turn himself in.
After several years in prison, Karl was paroled, even remaining reformed as his sister Selina turned back to crime as Catwoman and continued to battle Batman for many years afterward. He remained free on his parole, and was glimpsed in Superman Family #211 (1981).
Following his release, Karl Kyle remained good on his promise to go straight, donning his old King of Cats outfit once again, this time aiding super heroes over the years as a costumed ally. The King of Cats was most recently glimpsed attending a Zenith City super-hero convention following the Infinite Crisis, in the pages of Seven Soldiers: Bulleteer #3 (2006). Karl watched an awards presentation with many of the other attendees, and is shown to be drinking a toast to the late Jackie Pemberton.