Groot

"I am Groot."

- Groot's iconic catchphrase

Background
Groot was a Flora colossus from the planet, X. He eventually became friends with the genetically-modified organism known as Rocket. They committed crimes together. Several of his crimes were three counts of grievous bodily harm, fifteen accounts off escaping prison and three counts of mercenary activity. He was only limited to three words: "I am Groot."

Guardians of the Galaxy Vol. 1
In the year 2014, Groot and his friend, Rocket were on the planet Xandar looking for bounties on other people's heads. However, Rocket was the only one who was doing the hunting while Groot was drinking out of a water fountain. The tree's friend had been able to spot a young man named Peter Quill, who was wanted by his former caretaker and adoptive father, Yondu Udonta for forty thousand units. Just as they go to attack Quill, Gamora however had gotten there first.

While Rocket knocked Gamora out of Peter's reach, Rocket had ordered Groot to capture the former Ravager. However, Groot mistook Gamora for Peter until Rocket pointed out that Gamora wasn't the target. When Quill wasn't looking, Groot took the bag and put it over Peter's entire body. However, their plan failed when the group was taken into custody for disturbing the peace on Xandar.

While being presented by the Nova Corps, Groot, along with the others, were sent to the Kyln. On their first day in the Kyln, a monstrous inmate threatened Peter Quill, but was stopped by Groot, who stuck his two fingers into the inmate's nostrils. Rocket had told the prisoners that no one was to harm Quill, as he was "their booty" and if they wanted him, then they would have to go through either Groot or Rocket. This caused most of the prisoners to stay away from the new arrivals.

During the final battle with Ronan the Accuser, the old Groot sacrificed himself to save his friends from when the Dark Aster crash-landed.