The Joker is a fictional supervillain created by Bill Finger, Bob Kane, and Jerry Robinson who first appeared in the debut issue of the comic book Batman, published by DC Comics.
Harley Quinn is a fictional character appearing in American comic books published by DC Comics. The character was created by Paul Dini and Bruce Timm, and first appeared in Batman: The Animated Series in September 1992.
Power Girl, also known as Kara Zor-L and Karen Starr, is a DC Comics heroine. She is the Earth-Two version of Supergirl, from Krypton, and Superman’s cousin. She also posseses all of the main Kryptonian powers including superhuman strength.