While traveling the cosmos, Thanos witnessed the destruction of a peaceful race known as the Zen-Whoberis. There was one survivor: Gamora. He decided to take in this newly enraged young woman and turn her into a living weapon.
During her training with Thanos, Gamora believed that she killed all of the Badoon. Although, they later discovered that one, a princess, still lived on a planet about to fall into a black hole called Ubliex. Gamora befriended the princess and destroyed a treacherous group of Zen-Whoberis who were exiled there.
Next, Gamora appeared to Pip the Troll in an effort to track down Adam Warlock and use him to kill the Magus. Gamora nearly succeeded but Magus surprised her. With her mission seemingly scrapped, she called in her master Thanos. After Warlock defeated Magus and time reshuffled itself, Gamora left with Thanos to continue their work.
The Mad Titan sent Gamora out on a mission to become Warlock's "unofficial bodyguard" in an effort to keep this lynchpin in Thanos' plans alive. Thanos also needed to get rid of his charge because he knew that Gamora would oppose his plans for snuffing out all life in the galaxy.
Gamora began doubting her master's plans while on her way to Warlock, but her trip came to a stop when Drax smashed through her ship. After her run-in with the Destroyer, Gamora returned to Thanos, only to discover his true plans for cosmic genocide. In a fit of rage, the Titan attacked Gamora, practically killing her. Before she passed, Warlock to found her and she was able to pass her knowledge about Thanos' plans. Warlock later worked with the Avengers, Captain Mar-Vell, the Thing, and Spider-Man to stop Thanos.
Gamora remained inactive until the Silver Surfer and Drax found her living in the harmonious Soulworld inside the Soul Gem. After the Surfer explained that Thanos intended to use the Infinity Gauntlet and the Infinity Gems to destroy life, Adam Warlock decided to leave Soulworld with Gamora and Pip close behind. They both disappeared when Thanos prepared to use the Gauntlet, then reappeared when Warlock took control and defeated Thanos.
Not long after the events of this Infinity Gauntlet conflict, Warlock split up the Infinity Gems amongst a few individuals called Infinity Watch and granted Gamora the Time Gem, which gave her visions of the future. Having the Time Gem made Gamora uncomfortable as she didn't understand its powers. She fought alongside the Infinity Watch in a few conflicts, but eventually left the team and the gem behind to become a mercenary.
At some point, Gamora returned to the group, and even continued working with Warlock after the team came to an end. However, she left him too in order to continue her mercenary career. Gamora eventually ran into trouble when she was masquerading as Thanos. She found the real deal on Earth, plus five clones of himself that he created to end all life. Gamora helped stop the threat and agreed to work with Adam Warlock to acclimate a new Anchor of Reality, a young Earth girl named Atleza.
Months after the Annihilation Wave started wreaking havoc on the cosmos, the exiled former Accuser Ronan inadvertently gained Gamora's attention after landing in a backwater place called Godthab.
Gamora eventually settled in a mountain there and bonded with other female warriors, dubbed the Graces, including Nebula. During her ensuing battle with the former Accuser, Gamora admitted that she'd undergone a "cosmic makeover" that she hoped would rekindle her reputation as the deadliest woman in the universe. After the Annihilation Wave hit the planet, though, they banded together to end whoever set out to take them down.
After meeting up with Richard Rider and his resistance force, Gamora fell into a relationship of convenience with the last remaining Nova. She brought her specific set of skills to the battle that was ultimately won because Nova ripped Annihilus' guts out. Richard later revealed that Gamora's slaughter of Kree collaborators acted as the end of their relationship in his mind.
Soon after the first Annihilation conflict came to an end, Ultron used the Phalanx to infiltrate the Space Knights and nearly destroy Hala. Some enemies were turned into mindless slaves while the more useful ones, like Gamora, became Selects, which meant they retained a bit more of their personality. Gamora aided the Phalanx offensive against Nova, Peter Quill, and their allies. She used her intimate knowledge of Rider's mind to briefly turn him into a Select like herself.
Richard broke free of the programming after helping Select Gamora bring Drax into the fold as well. The controlled Gamora and Drax gave chase, but were ultimately returned to their natural states after New Mutant Warlock of the Technarchy removed the Phalanx programming from them both. Nova, Gamora, Drax, Warlock, and fellow Technarch Tyro then breached the barrier around Kree space and helped take down Ultron.
With this conflict wrapped up, Peter Quill put together a proactive team to prevent these kinds of threats from causing as much damage as the Annihilation Wave. And so, the Guardians of the Galaxy were born. Gamora enlisted, but didn't realize that Quill had used fellow member Mantis to push her and the others into doing so.
The team eventually got back together and became as much of a family as a fighting force. They helped save the universe during events like War of Kings, Realm of Kings, and the Thanos Imperative before spending a good deal of time saving the Earth from various threats.
As the team continued their adventures, Gamora met a fellow warrior woman named Angela with whom she developed an unbreakable bond. After responding to former teammate Carol Danvers' distress call, the Guardians landed on Earth in the middle of another Civil War. Upon discovering that Danvers had secretly kept Thanos on-planet without telling anyone, and that Quill knew about this, the angry and betrayed Gamora fought with Carol and ended her affiliation with the group.