Heather Douglas was only a child when the villain Thanos came to Earth, and killed her parents because they witnessed his arrival (her late father would later be turned into Drax the Destroyer). She was found by Mentor, an Eternal of Titan, and was brought to Titan to be raised. Intense study of mental and physical disciplines under the Shao-Lom Monks allowed her to tap into her latent mental powers, making her the equal of a Titan in combat, and superior to most. The cosmic entity known as the Dragon of the Moon secretly played on her arrogance and mentally influenced her, causing her to believe she was a superior being, above morals.

On Earth, she joined the Avengers. Her ego finally led her to mind-control the Avengers and conquer an alien planet. The Avengers sent her to Asgard to learn better ways; she was put "on probation" as a member of the Defenders. During this time she taught Hellcat some Titanian martial arts and even helped her develop some minor psychic powers. The Dragon of the Moon again began to control her, however, leading to the deaths of the Defenders team (although being superheroes, they all eventually got better).

The Titanian supercomputer ISAAC grew her a new body, and for a short time she travelled space with her cousin Sundragon; She also lusted after Quasar, but when that failed to pan out she had a couple of lesbian affairs, with ex-showgirl Marlo Chandler and former Captain Marvel Phyla-Vel. She was part of the Infinity Watch, guarding the immensely powerful Mind Gem, until they broke up and the gems went to others. Thanos tried to use her to get to Drax, but Drax ripped Thanos' heart out and for a time, all was well.

Moondragon got her wish to be Quasar's lover, but not the way she originally planned; Her no-longer-ex-girfriend Phyla became the new Quasar. Their romance is interrupted by the search for a savior of the Kree Empire, which turns out to be Adam Warlock. During this event, Moondragon discovers she has the power to become a literal Dragon, more powerful than ever, although she cannot return to human form. In an epic battle against the alien Phalanx and Ultron, Heather is killed again.

Powers

Moondragon has vast psionic powers including telepathy, mind control, and telekinesis. However, her powers require concentration, and if this is broken she is fairly helpless (She was once defeated by Rick Jones, by exploiting this weakness). She is skilled in several Titanian martial arts, and related mental and physical disciplines.

When she possessed the Mind Gem, her powers were increased to an unknown degree.

Moondragon also had a psychic bond to the Dragon of the Moon, and during a time of great stress, was permanently physically transformed into a dragon-like form with great strength and durability.

Alternate realities

Earth-398

Moondragon of Earth-398 was known as Priestess and was a member of the Queen's Vengeance.