Karai appears in various incarnations of the Teenage Mutant Ninja Turtles series, and is always affiliated with the Foot Clan. In some continuities, she's related to The Shredder, either via adoption or other means. In others, she simply is who takes over the New York Foot Clan following Shredder's demise. She often has a shaky alliance with the Turtles.
Karai is famous for having appeared as the Final Boss of the Genesis and Super NES versions of Teenage Mutant Ninja Turtles: Tournament Fighters shortly after appearing in the Mirage comic.
In the 2012 animated series, Karai is the name given to her by her adoptive father Oroku Saki, but in a plot twist, is revealed to be Hamato Miwa, the biological daughter of Hamato Yoshi.
In Rise of the Teenage Mutant Ninja Turtles, she is the biological daughter of Oroku Saki, but also the ancestor of Hamato Yoshi/Splinter, Donatello, Leonardo, Michelangelo, and Raphael. The Turtles affectionately call her "gram-gram". After Karai is killed attempting to bring down The Shredder, she merges her spirit with April O'Neil, empowering the latter immensely.