Cassandra "Cassie" Sandsmark, also known as Wonder Girl, is a fictional superheroine appearing in DC Comics. She was created by John Byrne and first appeared in Wonder Woman (vol. 2) #105 (January 1996). The second Wonder Girl, Cassie is a sidekick of Wonder Woman and has been featured as a member of the Teen Titans.
When Cassie was introduced, she was the daughter of an archaeologist, Dr. Helena Sandsmark, a friend of Wonder Woman's. To help Wonder Woman during an adventure, she borrowed 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 natural daughter of Zeus and Dr. Helena.
In 2011, DC relaunched its books with a new continuity called The New 52, and one of its major continuity changes was to Wonder Woman, establishing that she is a demigod and the daughter of Zeus. Cassie is reintroduced in the pages of Teen Titans as a superpowered thief with enchanted demonic bracelets; she is recruited into the Teen Titans superhero group by Red Robin, the former protégé of the superhero Batman, and has no obvious connection to Wonder Woman. Later, she learns that she is Wonder Woman's niece and Zeus's granddaughter. Her father is revealed as being a British super-soldier named Lennox Sandsmark who is Wonder Woman's half-brother and himself a son of Zeus. As before, Helen, Cassie's mother, is an archaeologist