"Wonder Girl" is a title passed down through three characters in The DCU: Princess Diana of Themyscira/Diana Prince, Donna Troy, and Cassandra Sandsmark.The first appearance of Wonder Girl was in Wonder Woman #105 of April 1958 where the title belonged to a young Diana. This Wonder Girl wore a very similar costume to the grown Wonder Woman: a red tank top with a golden eagle on the chest and golden crests on the edges, blue shorts with white stars, red ballet slippers to match Wonder Woman's boots, she wore her hair up in a ponytail, and wore Amazonian silver bracelets. The adventures of Wonder Girl seemed to capture the imagination of writers as her adventures on Themyscira (with a companion only dubbed Mer-boy) were often displayed in the Wonder Woman serial and she even starred next to Wonder Woman herself in some issues labeled Impossible Tales (which sometimes also featured an even younger Diana named Wonder Tot) that were composed by Queen Hippolyta as a sort of home movie spliced together from different periods of her daughter's life. While the impossible tales were not in continuity with the rest of the Wonder Woman series, Bob Haney brought Wonder Girl to the modern age of 1961 to fight along side Wonder Woman and her friends the Teen Titans even though she was still canonically a young Diana.Enter Donna Troy. The Teen Titans had received their own series with Wonder Girl still in the line-up even though her own creator, Bob Kanigher, had declared her Retgonned in Wonder Woman #158 in 1965 (although in a very tongue-in-cheek way). So what was Wonder Girl? A time-displaced Diana or another being all together? Marv Wolfman and Gil Kane sought to answer these questions in Teen Titans #22. This new Wonder Girl was not a young Princess Diana, she wasn't even of Amazon descent! She was a baby saved from a fire by Wonder Woman who was not able to save the child's parents and not being able to find new ones for her, Diana brought the young orphan to Themyscira to be raised as an Amazon. Given the same powers as Wonder Woman by a Purple Ray crafted by her Amazonian sisters, Donna Troy becomes Wonder Girl and dons an entirely new costume composing of a red full-body (sans sleeves) leotard adorned with stars, a belt with the Wonder Woman 'W' as its crest, black boots, wore her hair down to a past-the-shoulder style, and kept her bracelets.Here's where things get messy. As events such as Crisis on Infinite Earths and Infinite Crisis rewrote continuities and histories of heroes, Donna was a victim of multiple Origin Story syndrome:
- First came the origin given to her by the Teen Titans: an orphan rescued from a fire by Wonder Woman and raised by Amazons. This was expanded upon in the "Who Is Donna Troy?" arc in New Teen Titans, in which Donna learns the couple that died in the fire weren't her birth parents (and weren't very loving at all), and that her actual mother had died of cancer after giving her up to another couple who weren't able to keep her. It also turns out that her birth name is actually Donna (Hinckley), which she had coincidentally taken as part of her "Donna Troy" alias due to not knowing her birth name.
- Then came Who Is Wonder Girl?: Donna was saved from the fire that killed her assumed parents not by Wonder Woman, but by a Titan named Rhea. She was raised among 12 orphans from all over the universe, on a planet named New Cronus by the other Titans, as "Titan Seeds" that the Titans believed would one day save them. All the orphans were given superhuman powers and names of ancient cities, Donna being dubbed "Troy." The orphans were eventually stripped of their memories and placed back into their original places in the universe to await their destinies, with Donna believing she grew up in an orphanage for the first 13 years of her life (until her memories were restored). In this version Donna has no connections to Wonder Woman or the Amazons, and simply coincidentally took on the "Wonder Girl" name and modeled her uniform after the American flag.
- The Infinite Lives of Donna Troy: While trying to tie Donna back to her Amazonian roots but also keep the established continuity of the Titan Seeds, Donna became a literal mirror image of Diana. The magician Magala had taken a mirror's reflection of young Princess Diana and animated it as a playmate for the Princess, but the villain Dark Angel mistakes the new playmate for Diana herself and kidnaps her. Dark Angel dispersed her spirit across the multiverse, so that she may live multiple lives that all end with Dark Angel killing her at a moment of extreme tragedy. In at least one of the timelines, Donna becomes a super hero and encounters her sister Wonder Woman and Queen Hippolyta without being able to recall how she was related to them or even who they were. The timeline was ended with the death of Donna's son and Dark Angel came for her, but Wonder Woman and Queen Hippolyta intervened, saving Donna's life and destroying Dark Angel. With the destruction of Dark Angel, Donna returns to her original reality with her Amazonian powers intact and continues her life from that point.
- Amalgamation: Wonder Woman Annual #1 of volume 3 gives Donna a new origin based on elements of her last three origin stories. Donna was given life by Magala from Diana's reflection and kidnapped by Dark Angel under the mistaken identity of her sister. Dark Angel puts Donna in suspended animation and years pass until she is rescued. She is trained by the Amazons and the Titans of Myth and is raised as the second Princess of Themyscira. After a couple more years, she would follow her older sister into Man's World and adopt the name Wonder Girl and help create the Teen Titans.