Astra Logue

"Would you rather I stayed that terrified little girl, crying and waiting for you to come and rescue me? I would have been waiting a long time."

- Astra to John Constantine

Astra Logue is a major antagonist in Arrowverse, serving as a pivotal flashback character in Constantine and more recently, the final antagonist in the Season 4 of Legends of Tomorrow, becoming the main villain after Neron's defeat. She will presumably become the main antagonist of the upcoming Season 5 of Legends of Tomorrow.

Her child form was portrayed by Bailey Tippen in Constantine and by Melody Niemann in Legends of Tomorrow. Her adult form is portrayed by Olivia Swann.

Overview
Astra Logue was once an ordinary girl who was the unfortunate victim of exorcism conducted by John Constantine that went horribly wrong, resulting in her murder and wrongful damnation in Hell by the demon Nergal. Constantine was forever haunted by that act, desperately wishing for a chance to go into Hell and rescue her.

However, in the fourth season of Legends of Tomorrow, Astra later reemerged as an adult who sold her soul to the First of the Fallen. She was corrupted by her fear and anger at John Constantine for failing to save her, and prematurely aged into a grown woman who was allowed to enter the demon hierarchy rather than be tormented. Her current goal is to get a promotion within demonic hierarchy and has her revenge on Constantine himself.

Trivia

 * In the comics, Astra was never corrupted by her time in Hell and indeed stayed a child until John finally rescued her.