Moondragon is a character from the
Marvel Comics universe. Her real name is Heather Douglas. While traveling with her family, they drove too close to an operation
Thanos was conducting. Although they did not see anything, Thanos did not want to take any chances and destroyed their car, killing the people inside. However, thanks to Mentor, the ruler of Titan (as in the moon of
Saturn), Heather was saved and taken to Titan. There she was raised by
monks in the Kaluba sect, who helped her to develop her
mental powers.
She left Titan to seek out Thanos in order to exact revenge. Instead, she got in a fight with Iron Man. Since Iron Man is a hero, she was thought to be a villain for a while.
Later, she teamed up with Captain Marvel to fight Thanos in one of his bids to destroy reality. Because of her actions, the superhero community accepted her into their ranks. She was even a member of the Avengers for a short time. However, her arrogance got the best of her, and she left the Avengers to take over a small planet with her mental powers. Why? Because she thought she could run it better. Why else? The Avengers decided to intervene in order to free the planet. During the course of this battle, Moondragon killed Drax the Destroyer, who had been given the mind of Arthur Douglas (that would be her dad) by Kronos. After the magnitude of this act set in, she surrendered. Eventually, she was pardoned.
After the Infinty Gauntlet affair, Adam Warlock recruited her to the Infinity Watch. She was the guardian of the mind gem, which further enhanced her powers. Of course, now the mind gem no longer exists in the Marvel Universe. Still, Moondragon remains a formidable psychic, and tends to pop up in stories from time to time that call for that sort of thing.