Groot is a sentient, tree-like individual and frequent accomplice of intergalactic criminal Rocket Raccoon. Together, the pair travelled the galaxy picking up bounties until they met Star-Lord and Gamora on Xandar.
Real Name: Groot
Species: Flora colossus
Voiced by: Vin Diesel
1. Guardians of the Galaxy
Subsequently the four of them were captured and put in the Kyln, where they also met Drax. There, Star-Lord convinced them to assist him to sell the Orb for a massive profit and they managed to engineer a break-out and escaped.
However, when it was discovered that the Orb contained one of the Infinity Stones which was being sought out by Ronan the Accuser, Groot convinced his friends to risk everything to stop Ronan's plans to destroy Xandar and enslave the world.
During the war, Groot sacrificed his own life to save his new friends. However part of his destroyed body was planted by Rocket who regrew a new Groot, now called Baby Groot, as they joined the Guardians of the Galaxy.
2. Guardians of the Galaxy Vol. 2
As the new Groot slowly grew to the size of the original Groot, he stayed with the Guardians and endeavored with them on many adventures. Groot's tiny body and youthful innocence meant the Guardians spent much of their time trying to keep him out of harm's way.
They were hired by the Sovereign to kill the Abilisk, a powerful multi-dimensional monster that was trying to devour the Anulax Batteries, which powered the planet. After being chased by the Sovereign to Berhert because of Rocket Raccoon who double-crossed them by stealing the batteries, they met Peter Quill's father Ego.
He and Rocket, along with Yondu Udonta, were later captured by Taserface's faction of the Ravagers, but Groot was able to help them all escape. Groot then joined his allies and assisted them in destroying Ego and saving his friends, although Udonta lost his life during the battle. Remaining with the Guardians, Groot continued to grow and started exhibiting the personality of an adolescent.
3. Avengers: Infinity War
Both the young Groot and Rocket left the other Guardians temporarily to accompany the Asgardian Thor to Nidavellir in order to help him in his mission to stop Thanos from completing the Infinity Gauntlet.
After helping Thor obtain his weapon, Stormbreaker, Groot and Rocket travelled to Earth to help the Avengers battle Thanos' forces in Wakanda. Although Groot and his allies managed to kill off all of Thanos's forces, when Thanos himself arrived, he effortlessly defeated Groot and every other hero who tried to stop him and when he unleashed the full power of all of the Infinity Stones, Groot and all of the other Guardians except for Rocket and Nebula died.
4. Avengers: Endgame
Five years later, the Avengers managed to undo the effects of the Snap, resurrecting Groot. Alongside Winter Soldier, he left Wakanda through an Inter-Dimensional Portal and joined the Battle of Earth. In the aftermath of the battle, Groot attended Tony Stark's funeral and rejoined the Guardians, now including Thor, on their adventures.