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.
- 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.
Post-Crisis Titan Seed Donna eventually adopts a new super hero identity, Troia, to honor her Titan brethren. She also adopts a new costume: it is a black full-body leotard, much like her old costume, that is very sparkly, a silver belt with a simple circle crest, silver boots, and the traditional Amazonian silver bracelets.
With the Wonder Girl slot needing to be filled, John Byrne introduced Cassandra "Cassie" Sandsmark in 1996 Wonder Woman volume 2 #105. Cassie is the daughter of Archaeologist Helena Sandsmark and Wonder Woman fanatic. She is granted powers by the mythical objects of Hermes' sandals and Atlas' gauntlets. It is later revealed that she is a daughter of Zeus and asks for real powers be granted to her to fight the evil of man. She is granted them with the exception that her mother is given the choice to take them away if she feels it is necessary. Dr. Sandsmark, although initially alarmed by her daughters crime fighting, has never used this power as she respects her daughter's wish to be a super hero. Notably the only Wonder Girl to have her own comic series, Cassandra was given a six issue limited series titled Wonder Girl: Champion written by J. Torres. Cassandra has been a member of both Young Justice and the Teen Titans. As Wonder Girl Cassandra has worn many outfits, with these two being the best known: an ensemble including a black t-shirt with the Wonder Woman 'W' crest, a black leather jacket, gloves, red shorts, goggles, and a black wig to hide her identity. In her most recent outfit (pre-New 52), she wore a red shirt with varying sleeve length with the Wonder Woman 'W', jeans, and Amazonian bracelets.
The New 52 rebooted Wonder Woman's continuity and started off fresh. In the beginning, Cassie is the first Wonder Girl, although has been drastically altered. Cassandra is a thief with magical bracelets that dislikes being called Wonder Girl and wears Star-Spangled Spandex created by her bracelets. She is a member of the Teen Titans. It's eventually revealed that her father is Lennox, one of Diana's supporting character and her half-brother. This makes her Wonder Woman's niece and the granddaughter of Zeus. Meanwhile, Donna Troy was brought back as a villain in the DC YOU run of Wonder Woman — she's an evil, man-hating clay version of Diana. She died at the end of that run, but later appeared in Titans Hunt (2015), with no memory of her past. Titans (Rebirth) stars her alongside Dick Grayson, Wally West, Roy Harper, Garth and Lilith Clay. There, she remembers being an orphan raised by the Amazons... and it turns out that's not true, and instead she's the New 52 version who was given false memories by the Amazons.
- Aborted Arc: Teen Titans "Origins & Omens" back-up story foreshadowed a number of events which were supposed to affect the team, such as Blue Beetle hooking up with Wonder Girl. Nearly all of these were ignored when writer Sean McKeever was fired.
- Absence Makes the Heart Go Yonder: After Superboy's death in Infinite Crisis, Cassie and Tim Drake shared a kiss (which could be interpreted as referencing Sex for Solace as both of their significant others had just died), though Cassie broke away ran from the room crying. Then Superboy comes back from the dead. The pair are sure that he's going to be angry at them, but he's cool with it—hey, it's not like they knew his death was temporary.
- Action Girl: Whether we are talking about THE Trope Codifier in comics or her successors, any of the Wonder Girls are powerful and highly-trained warriors.
- Adorkable: Cassie started out as tomboyish mythology buff who made zero attempts to appear feminine but became shy and started stammering and trying to act more "girly" around guys she thought were hot outside of combat situations.
- Animal Wrongs Group: In one story, Wonder Girl has to deal with an animal rights group who thought that hydras were nice friendly critters.
- A Tragedy of Impulsiveness: In Amazons Attack, Queen Hippolyta tricks Cassie and Kara into Supergirl and believing she can end the war if they kidnap the President and bring him to her in order to engage in peace talks. Predictably, their plan goes awry: the Amazons shot the Air Force One down and almost killed the President, and Kara and Cassie's reputations suffered a severe blow. After fending an Amazon squad off, Kara flies to New York to help, although Cassie points out they got into this mess because of acting rashly and unthinkingly.Wonder Girl: But we were only trying to—
Supergirl: Doesn't matter. I have to make up for this somehow, before it's too late. I have to balance the scales.
Wonder Girl: How? By flying off half-cocked again, after what we just did...?
Supergirl: I can't do nothing, Cassie!
- Back from the Dead: Donna Troy died at a Superman robot's hands in Titans/Young Justice: Graduation Day #3 and was reborn right before Infinite Crisis.
- Bash Brothers:
- Donna and Diana are this, and the two of them built a similar relationship with Cassie Sandsmark.
- Donna and Dick Grayson are often written this way in the pages of Teen Titans.
- Big Brother Mentor: Diana to Donna, although it's been a while since Donna's actually been mentored by Diana. Donna also serves as an older sister to Cassie.
- Blonde, Brunette, Redhead: The originals Supergirl -Kara Zor-El, blonde- Wonder Girl -Donna Troy, brunette- and Batgirl -Barbara Gordon, redhead- are this in the original universe and Super Best Friends Forever.
- Blush Sticker: For whatever reason, Wonder Girl has permanent blush stickers in Teen Titans: Year One.
- Brainwashed and Crazy: In Justice, Donna and the rest of second-generation heroes (the Teen Titans, Supergirl, Batgirl, the Marvel family...) were mind-controlled by the Legion of Doom.
- Breaking the Bonds: In Supergirl (2005) story "Girl Power", Cassie tries to bind Kara with her magic, unbreakable lasso, but Supergirl shrugs it off.
- Broad Strokes: One of the approaches attempted by DC prior to Infinite Crisis to reconcile Donna Troy's backstory was every origin story is true.
- Canon Discontinuity: DC ran an event called Origins & Omens, which had each book featuring an ominous short story hinting at future plots. The Teen Titans story featured several major revelations, such as Blue Beetle kissing Wonder Girl; a plot point later ignored.
- Cat Fight: Cassie and Kara got into one in Girl Powerwhen Cassie wrongly thought Conner was cheating on her with Kara.
- Civvie Spandex: In a deliberate homage to her then-fallen boyfriend, Cassie's One Year Later costume consisted of jeans and a red tank top with her logo on it. Of course, most of her earlier outfits during the Young Justice era were not much different.
- Clark Kenting: Originally Cassie had the ingenuity to wear a black wig and goggles, though even then her costume was mainly thrown together from what was already in her closet. She ditched them after a situation where she had to chose between maintaining disguise and saving the day. In the version of Teen Titans starting in 2003, she does not have a secret identity, which caused problems finding a school that would take her.
- Continuity Snarl: Donna Troy's origin is infamously convoluted, it even gets it own page.
- Defeat Means Friendship: Kara and Cassandra became friends after the former defeated the latter in 2005 story arc "Girl Power".
- Flying Brick: Wonder Girls have the Amazonian Pack: Super Strength, Super Speed, Super Toughness and Flight.
- God Couple: Cassandra Sandsmark and Conner Kent (Superboy) are each other's main love interest and two of the most powerful heroes in The DCU.
- Heterosexual Life-Partners:
- Donna Troy and Dick Grayson (Robin/Nightwing). They have been childhood friends and partners in the Teen Titans and the Justice League of America, but Donna is one of the few DC females who is not romantically interested in Dick.
- Cassandra Sandsmark and Kara Zor-El -Supergirl- are very intimate friends.
- Legacy Character: Donna and Cassie are Diana's successors. Donna was Wonder Woman for one year after Infinite Crisis.
- My Sister Is Off-Limits!: Falling under the "extended family" (of sorts) category, Wonder Woman does not approve of Conner's relationship with Cassie. Demonstrated by the time the latter two were kissing in midair and Wonder Woman grabbed Superboy by the collar and flung him into a mountain range.
- Proud Warrior Race Guy: Per their Amazonian heritage.
- What the Hell, Hero?: After Infinite Crisis, Wonder Woman decides to retire for a while and takes off for parts unknown without explaning Donna and Cassandra why. In Wonder Woman Vol. 3 issue #2, Cassie vents her anger on her:Cassandra: Diana...? Is it really you?
Diana: It's really me, Cass. You okay?
Cassandra: Am I okay? Let's see... The gods abandoned us. Paradise Island disappeared. My boyfriend was murdered... and the person I looked up to more than anyone else in the world... left without saying a word.
Diana: I was trying to protect you.
Cassandra: You deserted me. Me AND Donna. And now, for all we know, she could be dead.