Saturn Girl (Imra Ardeen) is a superheroine appearing in comics published by DC Comics. A talented telepath from the 30th century, Saturn Girl is a founding member of the Legion of Super-Heroes. Imra's "Saturn Girl" title refers to her homeworld of Titan, Saturn's largest moon. There have been three versions of Imra since her original debut, separated by the events of the limited series Zero Hour: Crisis in Time! and Infinite Crisis.

Saturn Girl has appeared in various media outside comics, primarily those featuring the Legion of Super-Heroes. Kari Wahlgren voiced her in the animated series Legion of Super Heroes (2006), and reprised the role in Young Justice. In live-action, Saturn Girl has been portrayed by Alexz Johnson and Amy Jackson in Smallville and Supergirl respectively.

Saturn Girl first appeared in Adventure Comics #247 (April 1958), and was created by Otto Binder and Al Plastino.

During the Silver Age of comics, 30th-century Earth is a member of the United Planets and home to its military branch, the Science Police. As a teenager, Imra Ardeen leaves Titan to join the Police, during which she, Rokk Krinn, and Garth Ranzz foil an assassination attempt on fellow passenger and billionaire R. J. Brande. At Brande's urging, the three form the Legion of Super-Heroes, inspired by the legacy of Superboy, who they later recruit from the 20th century.

Just before the leadership elections of 2975, Saturn Girl learns that a Legionnaire would die during an attack on Earth and decides to take on that responsibility herself. Using her telepathy, Imra forces the other Legionnaires to vote her leader and then orders them not to use their powers during the attack, preventing them from rescuing her. However, Lightning Lad defies her orders and dies in her place. Saturn Girl attempts to sacrifice herself to resurrect Lightning Lad, but her plan is foiled by Proty, the pet of Chameleon Boy, who dies instead.

Romantically, Lightning Lad (Garth Ranzz) had pursued Imra for some time, but she had repeatedly rebuffed his advances. After he sacrificed his life for her own, she understood the depth of his feelings and came to realize that she returned them. After dating for almost ten years, Garth proposes marriage, but Imra initially rejects his offer due to a Legion rule which prevents members from being married and remaining in active duty at the same time. Sometime after consulting with her mentors on Titan, Imra relents and marries Garth. Several months later, all active Legionnaires are captured and the reserves are forced into action. Imra's telepathic skills are instrumental in the Legion's eventual victory, and as a result the rule barring married members is repealed. Imra and Garth return to active duty until Imra gave birth to their son, Graym, after which they both retire to raise him. Unbeknown to the couple, Graym had a twin, Garridan, who was stolen at birth by Darkseid and transported into the past, where he was transformed into the monster Validus. After learning that Validus is her son, Saturn Girl convinces Darkseid to return him to his original form.

Saturn Girl rejoins the Legion after helping stop Universo from conquering Earth. During the "Five Year Gap", Earth's government becomes hostile to the Legion, and Garth is incapacitated by a Winathian plague. Disillusioned by the government and feeling needed more at home, Imra resigns from the Legion and returns to Winath to become a farmer. She and Garth have two additional children, daughters Dacey and Dorritt.^{[volume & issue needed]}

After the reboot of the Legion in Zero Hour: Crisis in Time!, Imra remains known as Saturn Girl, and a founder of the Legion along with Cosmic Boy and Live Wire. Her design was changed from previous versions, combining some elements from past uniforms. The top and pants of her uniform are similar in design to her red and white uniform, but now colored pink instead of red, and has the familiar Saturn logo.