Gamora is an orphan of Zehoberei, who was adopted by the warlord Thanos when she was a child. He trained her to be an assassin by pitting her against Thanos's other adopted daughter, Nebula, who would always lose and would be painfully augmented by having body parts replaced with cybernetics, causing a great rift between the two sisters. Gamora was also given implants, but far less severe. Gamora became known as the "deadliest woman in the whole galaxy." But Gamora's conscience got the better of her, turning on Thanos by joining the Guardians of the Galaxy.
Thanos kidnapped Gamora to take him to Vormir, where she hid the Soul Stone from him. He discovered from the Red Skull, who had been marooned there, that he would have to give up the one he loved to receive it, and in an ironic twist, it was Gamora, who he threw off a cliff and fell to her death. Thanos succeeded in his quest to collect all the Stones, which he could the combined power to extinguish half of the universe's population in 2018.
It took five years for the Avengers to formulate a new plan to go back into the past and collect the Stones before Thanos did. Only, during the reformed Nebula's (who had reformed) trip in 2014, she accidentally alerted the 2014 Thanos. Thanos, with a still committed Gamora, was able to follow them forward to 2023, where he began an all-out war against the heroes of Earth, which included Gamora, who was able to be convinced by present day Nebula.
At the war's end, Thanos and his army were decimated and turned to dust by Tony Stark (Iron Man). In a deleted scene, Stark's close allies take a knee, except for a spared Gamora, who's still not quite the reformed figure the other Gamora had been, uses this opportunity to slink away.
- Guardians of the Galaxy (2014)
- Guardians of the Galaxy Vol. 2 (2017)
- Avengers: Infinity War (2018)
- Avengers: Endgame (2019)