She was originally introduced in Kevin Eastman and Peter Laird's comic book series Teenage Mutant Ninja Turtles in 1992. Since then, she has appeared in several different TMNT comics, cartoons and films, as well as in about a dozen video games.
In incarnations in which she isn't brought in to clean up Oroku Saki's mess, she is usually of some relation to him. However, in her original comic incarnation, Karai was completely unrelated to the Shredder and was actually higher in the Foot Clan's global hierarchy. Karai is a shaky ally to the Ninja Turtles as much as she is a fierce foe brought forth by her sense of honor. In most works, she shares an ambiguous rivalry and love-hate relationship with the Turtle Leonardo. In the animated and game adaptations, Karai is primarily voiced by Karen Neil, Zhang Ziyi and Kelly Hu, while Minae Noji and Brittany Ishibashi portray the character in live-action films.