Cassandra "Cassie" Sandsmark, a.k.a. Wonder Girl, is a fictional character, a DC Comics superheroine. Created by John Byrne, and first appearing in Wonder Woman (vol. 2) #105 (January 1996), she is a sidekick of the popular superhero Wonder Woman and also a prominent member of the superhero group the Teen Titans.
When Cassie was first introduced in 1996 Wonder Woman comics, she was the daughter of an archaeologist who discovered magical artifacts which bestowed upon Cassie superpowers, with which she fought crime as Wonder Girl. Later, Zeus, king of the Greek gods, grants her real powers. Later revelations showed that Cassie was in fact a demigoddess and the daughter of Zeus himself.