Teekl

Teekl, is a DC Comic villain and Klarion the WItch Boy's pet cat.

Batman the Animated Series
While Bruce Wayne and Tim Drake were at an auction, they come across Klarion, and his pet cat; Teekl. They both wanted a mystical branding iron that originally belonged to Morgan le Fay. After Bruce won the auction and gave it to Jason. Furious, but still intent on getting the branding iron, Klarion sent Teekl to steal it. Went Teekl tried to steal she shapeshifted into a humanoid of woman and cat. She easily fought Bruce, Tim and Etrigan easily and managed to steal the Branding Iron. After Batman managed to take Branding Iron form Klarion, Klarion sent Teekl to kill Batman and take back the Branding Iron. But Batman manage to press the Branding Iron, which granting him full control over Teekl. After Klarion was defeated and was sent to his room, it's likely that Teekl was imprisoned as well.

Young Justice
Teekl is Klarion's pet cat as well. When Klarion casts a spell on Teekl it turns into a giant cat-like monster instead of a humanoid cat girl.

Trivia

 * It's unknown what Teekl's gender really is. In Batman the Animated Series, Teekl is a female, but in Young Justice, Teekl is a male.