Teenaged Courtney Whitmore was born and raised in Southern California, and was the quintessential Valley Girl. The daughter of Sam Kurtis and Barbara Whitmore, after her parents divorced, her mother found a new husband named Pat Dugan. Together, they moved the family out to Blue Valley, Nebraska, the childhood home of Flash Wally West, and a far cry from the hustle and bustle of living in LA. Courtney was very unhappy with the big move, and she didn't like her stepdad new all that much either.
One day, while going through some of her new stepfather's personal items, Courtney found the old crime fighting equipment of Sylvester Pemberton's, once better known as the Golden Age hero the Star-Spangled Kid. Soon, she realized that her stepfather Pat was once Stripesy, who was famous for being the only adult sidekick to a teenage Super Hero ever. Being a teenager herself, Courtney found the perfect way to humiliate her step dad with this new found knowledge. Wearing a star-spangled costume of her own to a school dance as a way of making fun of him, but they were soon attacked by the villainous Dragon King's henchmen. It was then that Pat Dugan debuted his new S.T.R.I.P.E. Armor to stop them, and along with his Courtney, they saved the day together.
Putting aside their differences, the two decided to become a crime fighting team, Star-Spangled Kid and S.T.R.I.P.E. As it turned out, Courtney's arch rival in high school, the ever popular mean girl Cindy Burman, was the daughter of Dragon King's, and took the codename Shiv. The two became arch enemies both on and off campus. During her Blue Valley adventures, she teamed up with the current bearer of the mantle of Starman, Jack Knight. When Jack decided to retire from the Super Hero life, he passed down his cosmic rod to Courtney, after having seen her in battle. Carrying on the Starman legacy, she changed her codename to Stargirl. She became a junior member of the newly reformed Justice Society of America not long afterwards.
As Stargirl, Courtney finds that she must deal with the legacy of Sylvester Pemberton, whose Super Hero name she carried. She confronts the monster Solomon Grundy, who murdered Pemberton. Courtney also encounters Merry Pemberton, the sister of the original Star-Spangled Kid who went by the name Merry, Girl of a 1,000 Gimmicks. Although she was at first leery of this teen hero taking on the mantle of her brother, Courtney eventually earned her respect, and received her blessing.
Courtney's romantic life becomes complicated, when JSA member Captain Marvel (A.K.A. Shazam), begins to develop feelings for her. Although he is actually teenager Billy Batson in reality, to the rest of the world, they see him as a full grown man, and his relationship with Courtney is frowned upon by the other members of the team, causing him to leave rather than reveal his secret identity.
Post Infinite Crisis (2005-2010)
After the world shaking the event known as the Infinite Crisis, the JSA disbanded. But not long after, the original surviving members Green Lantern, Flash and Wildcat reformed the team, and Stargirl was once again a member of the group. She soon befriended the original Red Tornado Ma Hunkel's granddaughter, Maxine Hunkel, and helped her become a legacy hero herself, when she took on the name Cyclone.
Not long after, the Justice Society split into two teams, with many of the younger members becoming the JSA All-Stars, including Courtney. But Stargirl is uneasy about leaving the main JSA, until Power Girl convinces her that she is an inspiration to many of the younger members of the team who see her as a role model, so she decides to stay on board. Courtney has a romantic interest in the older hero Albert Rothstein, A.K.A. Atom Smasher, but it is a relationship that never really takes off due to the age difference.
The New 52 (2011—2016)
After the DC Universe history is once again rebooted due to events of Flashpoint, Stargirl's history is altered. There was never a Justice Society in this new reality, and the first time we see Stargirl is as a member of the government sanctioned Justice League of America, which was put together by Amanda Waller. Much of her origin story remained the same as before, but only now both the original Star Spangled Kid and Stripesy were not Golden Age heroes.
There is a new tragic element to this backstory, as when Stargirl defeated the criminal Shadow Thief, he later got his revenge on her in a truly horrific way. One day when she returned home from adventuring, she found Shadow Thief had ransacked her home, seriously wounded her parents, and her younger stepbrother was killed. This made Courtney reevaluate her career as a Super Hero, but she ultimately decided to honor her brother by becoming the best hero she could be. It was not long after she decided to become a member of the Justice League of America, and later, the Canada based Justice League United.