Kara In-Ze is Supergirl in the DC Animated Universe. She comes from from Krypton's "sister world" of Argos. The character is depicted as a headstrong and independent teenage girl who was placed in suspended animation before the conditions on Argos became inhospitable.
Bruce Timm and Paul Dini intended to use the original Supergirl, Kara Zor-El, but were denied by DC Comics, due to DC's then-present edict that Superman was to remain the only surviving Kryptonian.
The daughter of planetary chief physician Kala In-Ze (In-Ze was the last name of Kara Zor-El's mother Allura), Kara was the only survivor of her planet, the rest having died when their suspended animation units suffered damage over time. While on a space exploration trip, Superman discovers Argos and consequently Kara. Clark arranges for the Kents to take Kara in while she adjusts to life on Earth, and upon visiting Clark in Metropolis, she wears glasses and a brunette wig with a ponytail to pose as Clark's cousin Kara Kent. This Supergirl shares Superman's vulnerability to kryptonite; she also suffers from cheimatophobia (fear of cold), due to her experiences prior to her time in suspended animation. Kara is written as eager to take up a position at the right hand of Superman, but Superman thinks she is too young and unready, despite the fact that she and Jimmy Olsen, who struck up a friendship at once, were critical in ferreting out an early connection between Intergang and Granny Goodness. Kara becomes friends with Batgirl in The New Batman Adventures episode "Girls' Nite Out", though their meeting is played for laughs and the girls depicted as somewhat inept. However, this friendship was again referenced in the Justice League season 2 episode 'Comfort and Joy', in which Superman (Clark) asks his parents "Where's Kara?" and they reply "Skiing with Barbara."
The costume worn by the animated Supergirl is used by Linda Danvers in the 1996 Supergirl comic book series. She continues to use that same costume in her first appearance in the first episode of Justice League Unlimited, where Nicholle Tom reprises her voice-acting role. In the third season of JLU, Supergirl appears in a new outfit, (the more traditional blue top with red miniskirt) that resembles Kara Zor-El's post-Crisis costume. Plus, She becomes an excellent hand-to-hand combatant, having trained in various forms of unarmed fighting such as Taekwondo, Kickboxing, Karate, etc. In the episode "Far From Home", the explanation is that the costume was altered to look more like Superman's mentioned in a discussion between Green Arrow and Superman.
Supergirl appears in Justice League as a mourner at Superman's funeral when he was presumed dead but wasn't; she does not wear her Kara Kent disguise. Rather, she has her blonde hair exposed and is attired in sombre black, a discrepancy that was never addressed considering that throughout the rest of her civilian appearances, she is in her disguise.
It is revealed that scientists from Project Cadmus create Galatea, an evil clone of the program's Supergirl (Kara) for nefarious purposes. The clone is a more mature version of Kara, and in appearance and costume is a homage to Power Girl. Kara, accompanied by Green Arrow and Question travel to S.T.A.R. Labs to investigate. From this episode on, Green Arrow becomes a sort of father figure to Kara and frequently discusses her with Superman. In the episode "Far From Home", Green Arrow tells Superman that he and Black Canary planned on bringing Supergirl out to celebrate her twenty-first birthday.
In the Justice League Unlimited episode "Far From Home", Supergirl, along with Green Lantern and Green Arrow, encounter Legion of Super-Heroes members Brainiac 5 and Bouncing Boy. They have brought the three modern heroes to the 31st century to aid them in defeating the Fatal Five, who have implanted mind control in all Legionnaires. However, Brainiac 5 tells Green Lantern and Green Arrow that 30th century history says that Supergirl never returned to her own time; Brainiac 5 and Bouncing Boy assume this indicates that she will die while on this mission. As Kara experiences the techonology and society of the 30th century, which is similar to that of her lost homeworld, she becomes more and more conflicted about returning to the past, where she has never felt that she fits in. Finally, she and Brainiac 5 develop romantic feelings for each other, and when Green Lantern and Green Arrow prepare to return to the past, she tells them that 30th century history will be fulfilled since she is staying in the future as a member of the Legion. DC Comics introduced Kara into their Legion of Superheroes monthly comic soon after renaming it 'Supergirl and the Legion of Superheroes.' Kara had also been a member of the Legion prior to her first comic incarnation's death in 'Crisis on Infinite Earths.' She also had a relationship with Brainiac 5 during this time.