Meriadoc Brandybuck (aka Merry) is one of four Hobbit representatives in the Fellowship of the Ring. He descends from a long line of hobbits who hold influence in a part of the Shire separate from the standard four Farthings, known as Buckland. While Frodo and Sam began their journey from the Shire, he rendezvoused with them not long after they started. In the movie, he is seen hiding in the hollow under the tree roots from the Ringwraith, but in the book he actually did not join the party until after that scene. He ended up becoming a member of the true Fellowship in the Council of Elrond. He was separated from them at Amon Hen, when Boromir was slain by the Uruks. He and Pippin were captured and carried off by them toward Isengard, but they managed to escape and fled into Fangorn Forest, where they met Treebeard, on of the oldest of the Ents, and they convinced him and the other Ents to lat siege to the tower of Orthanc and its production facilities for Saruman's army. After the Orcs there were killed, they rejoined the whole Fellowship, except for Boromir, now dead, and Frodo and Sam, who were still trying to enter Mordor.
Merry went on to Rohan, and he became an esquire of King Théoden, who cared little to let him fight. The young hobbit, however, sneaked into the cavalry with Éowyn. He fought alongside her in Pelennor Fields during The Siege of Gondor. He helped her defeat the mightiest Nazgûl, the Witch-king of Angmar, by stabbing him with his sword. However, in doing so, he was cursed by a black magic, along with Éowyn and had to be taken to the Houses of Healing, where they were cured of their curse by Aragorn and his use of the Athelas plant. He was recovered quickly enough to enter battle again, when the remaining forces of Rohan and Gondor marched upon the Black Gate.
After the One Ring was destroyed, he reunited with Frodo and Sam and remained with them in Gondor for a while. In the literary version of The Return of the King, while trekking along the western side of The Misty Mountains, they encountered Saruman and Grima Wormtongue. Out of pity, he gave Saruman his share of pipeweed, but when Saruman proved rude, he demanded it back, but the old wizard refused, and they left him. When they arrived in the Shire again, they saw that it had been taken over by what appeared to be half-Men, half-Orcs. He joined Frodo, Sam, and Pippin in rallying their hobbit brethren and revolting against their unprepared oppressors, and they discovered that Saruman had orchestrated it, and he was then stabbed in the back by Grima, who was soon after killed by hobbit arrows. With the restoration of the Shire, he returned to his normal life and later became the lord of Buckland.