Groot

Origin
Groot is a Flora colossus from Planet X the capital of the branch worlds. The sapling that will come to be known as "Groot" came from an "Enobled Sap-line" and gifted in quasi-dimensional super-positional engineering. Groot did not get along with his fellow saplings but instead preferred the company of the "Maintenance Mammals" who the other saplings treated with prejudice. After Groot killed another sapling to defend a maintenance mammal it was brutalising, he was exiled of the planet by the "Arbor Masters".

Guardians of the Galaxy
Into his adulthood Groot found himself in Kree space, where he was promptly captured and imprisoned. While in jail he formed a rapport with Rocket Raccoon and was assigned to a covert ops team lead by Starlord, whose goal was to assault Hala and defeat the Phalanx. His body was mostly destroyed, but a small twig of him split off, preserving him, traveling in the care of Rocket Raccoon, fitting easily in his hand. He can grow back to his full size in time.

Mojo TV
Groot and Rocket Raccoon are having a libation in a low-down dirty spacer bar in low-down dirty spacer space when they are accosted by a group of Badoon who attempt to arrest them for 'Crimes against the Royal Brotherhood'. A quick shootout ensues and Rocket creates an avenue of escape by shooting holes in the beer barrels causing the saloon patrons to stampede for the free beer. The duo make a hasty exit and are soon rocketing away when they find themselves pursued by Badoon Attack Cruisers. Rocket orders Groot to take evasive action while he goes to boost the stardrive to allow them to escape. He finds the stardrive compartment empty and the scene cuts to a shot of the surprised Rocket with a cliffhanger closing credits and Mojo proclaiming "Best Pilot Episode Ever!". They then find themselves staring at an empty compartment where a stardrive should be and questioning why they are hearing voices like suddenly their lives just got a narrator or something. Their ship blows up and they appear in space in combat space armor bewildered at what just happened and how they got there. They target their Badoon attackers forcing one of the pilots to eject. They squeeze into his craft and it begins to plummet to an ice planet below. Mojo calls for the scene to cut and hit the Bio-Stasis on his stars. He proceeds to plan for the next scene expecting to make enormous money on the show. In the background, Rocket's Timely Inc. Shipment Processing Device analyzes the situation and informs the duo they are caught up in an artificial dramatic construction. They blast through a wall realizing they are in a "Flarkin' TV Studio" and are confronted by a hologram of Mojo who opens fire with real weapons.

Groot and Rocket Raccoon are transported to the Mojoverse by the inter-dimensional TV producer known as Mojo. He has decided to use the pair in his latest reality television show. He recruits various criminals that the heroes have fought in the past. He places the pair in scenarios were they would have to battle them again, however if an innocent life form was caught in the crossfire, they would be killed in the process. [4] As the duo moved from one scenario to another, Mojo began advertising action figures with a collection pack that allows buyers to assemble their own 12" Groot figure after collecting all five. The demand was so high, Mojo stand to make a fortune until the Timely Inc. Shipment Processing and Analysis Device decides to take control of the situation and holds a B-00-M Meson Beam Gun at Mojo's face. It allowed the reality system to stop just long enough for the heroes to escape. They confront destroying Mojo who is revealed to be a robot controlled by Major Domo.

Return
Groot, along with the rest of his team, aided the Avengers in fighting the returned Thanos.Thanos managed to get a Cosmic Cube from the United States Army, with which he escaped to Moord, the homeland of the Badoon. The Guardians arrived to the Avengers Tower and informed the Avengers about the situation. They joined the Guardians to fight Thanos and the Badoon. After Thanos apparently killed the Elders of the Universe, to impose his supremacy, he became one with the Cosmic Cube and killed the Avengers as well as the Guardians. But actually, they were sent to the Cancerverse along the Elders, there, Tony Stark found that Thanos' weapon wasn't actually a Cosmic Cube and that it had defects. They bargained with the Collector, in exchange of a weapon capable of deactivating the "Cube" and return to Earth, the Avengers and the Guardians would let Thanos to be defeated by the Elders. With the help of other members of the Avengers, Thanos was defeated and sent to punishment by the Elders.

Marvel Cinematic Universe
Groot and Rocket are bounty hunters. On Xandar he and Rocket met Peter Quill and Gamora. They were trying to turn in the bounty on him when they all got arrested for causing mayhem in the streets. They were sent to the Kyln prison where the four met Drax. Upon learning that Gamora was planning on selling the Orb of Morag to The Collector at Knowhere for forty billion Units, the four agreed to break out together to split the money.

Once at Knowhere, Groot, Rocket and Drax took part in some gambling. After a scuffle that a drunken Rocket caused he went to take the Orb to the Collector with Quill, Gamora and Rocket. After learning that the Orb contained something called an Infinity Stone, the Collector's distraught assistant touches it, causing an explosion. Groot managed to grab Rocket and jump clear of the explosion. When they return, Gamora had decided that the stone is too dangerous to leave in the Collector's care. However, they then discover that Drax had called Ronan to Knowhere. A battle took place and Groot, Rocket and Drax became separated from Gamora and Quill.

Groot later pulled Drax out of a pool of yellow water which Ronan threw him in and resuscitated him. Rocket then rejoined them, announcing that Gamora and Quill have been captured by the Ravagers. Though Rocket wanted to get as far away from the conflict as possible, Groot insisted that they rescue their friends, reminding that they're the only one they've ever made. They attack Yondu's carrier, demanding that they release their friends, only to learn that Quill had made up with the Ravagers, who have agreed to help fight Ronan.

After being reunited with the others they formed a plan with the Ravagers to stop Ronan's attack on Xandar. Groot was with Gamora, Drax and Quill as they entered Ronan's ship and helped Drax and Quill fight off Ronan's men. When Quill shot Ronan and thought he had killed him, the ship began to crash. Groot made a shield for his friends by cocooning them in his own body. Rocket, saddened by this, asked why he would sacrifice himself for the team to which Groot replied, "We are Groot." When the ship crashed Groot was destroyed but Rocket found a piece of his body and put it in a flower pot. After the battle, as they left in Quill's ship the piece began to grow. While listening to Quill's Mix Tape the regrown "baby" Groot began to dance to the music, unbeknownst to Drax who had his back to him.

Physiology

 * Flora colossus Physiology: Groot has abilities native to his species:
 * Strength: Groot's tree like form provides him great strength. He is the strongest member of the group, being able lift many heavy objects including several men on just one arm.
 * Durability: Groot's hide is composed of wood dense enough and durable enough to make him immune to most conventional weapons, including gunfire and fire which would consume most woods.
 * Cellular regeneration: Groot has an amazing healing factor and has been shown to be able regrow everything from a missing limb to his whole body.
 * Spores: Groot has the ability to produce tiny spores that create light as shown when the Guardians arrive on Ronan's ship.
 * Elasticity: Groot has the ability to stretch his arms and legs for long distances.
 * "I am Groot!": Although Groot is able to understand common speech his own speech is limited to the phrase "I am Groot", but he also managed to say two new words: "We" and "are". However, Rocket, and perhaps Peter Quill, are able to understand him.