Little is known about the life of Nebula before the time she hijacked Sanctuary II, the solar orbiting satellite built and used as a base of operations by Thanos. A short time before Thanos became permanently transfixed between life and death, Nebula sent a small band of her most trusted aides to Sanctuary II to repair its hyperdrive engines and teleport the station out of the solar system. The underlings were met by the Avenger then known as Captain Marvel, who had been sent to investigate possible activity. Nebula's minions warped the satellite out of the solar system with Captain Marvel aboard and rendezvoused with Nebula. She planned to conquer the Skrull empire, which was then in chaos after the destruction of its throneworld by the planet-devourer Galactus. Not knowing how to return home, Captain Marvel pretended to go along with Nebula's scheme, but actually helped the Skrulls evacuate the outpost world Nebula was intent on destroying.
The Avengers eventually located their missing member and allied themselves with the Skrulls to oppose her. Before the Avengers could catch up to Nebula, she annihilated both the Skrull outpost and the planet Xandar, home planet of Firelord. In battle with Nebula, the Avenger Starfox, brother of Thanos, learned that Nebula was apparently Thanos's granddaughter and thus his own grandniece. Shortly thereafter, the virtually omnipotent Beyonder, curious about the Avengers, arrived, and in an attempt to help the Avengers vanquish Nebula, helped her and her minions to escape by teleporting them out of the Andromeda Galaxy.
Sometime after all this, while Firelord and Starfox were searching known space for Nebula, Thanos was reborn. One of his first tasks was to reclaim Sanctuary II. When he found Nebula, she claimed to be his granddaughter. He torched her body and left her on the brink of death, where she hovered until the affair of the Infinity Gauntlet. For whatever reason, Thanos left Nebula to roam around his shrine as he battled all manner of beings to keep the Gauntlet. After Thanos defeated Eternity and left his body, Nebula claimed the Gauntlet and fully restored herself to life as she achieved omnipotence. She eventually lost the Gauntlet to Adam Warlock and was placed in the custody of Firelord and Starfox.
Later one of her crew freed Nebula from her cell on Titan, finding her in a catatonic state. After surgery to restore her to her former mental capacity (if not her former looks) she battled the Silver Surfer.
Nebula later resurfaced as a member of the Graces, Gamora's group of female warriors.
Among the advanced alien technology at her disposal was once the Sanctuary II, a starship of 10,000 crewmen of various species and armed with hundreds of energy weapons as well as a hanger deck holding hundreds of fighter craft.
Nebula wore wrist blasters that produced blasts of concussive force.