John Locke was one of the middle section survivors of Oceanic Flight 815. Before the crash his father conned him for one of his kidneys and later pushed him out of a window, breaking his back, causing him to have to be in wheelchair. After this he spent the next four years of his life paralyzed from the waist down and looking for his purpose in life. He was then told by Matthew Abaddon that he must attend an Australian Walkabout after which he found himself aboard Flight 815. His paralysis was immediately healed upon crashing on the Island, which ultimately led him to believe that he had some sort of special connection to the Island. John was very handy with tools and a good hunter of boar and other animals of the Island, which proved to be very helpful in the survival of the group. Seen as antithetical to Jack Shephard, he and Jack were philosophical opposites and used to share leadership among the survivors.
When Locke discovered a Hatch on the Island, he was determined to open it, insisting that everything happened for a reason. He opened it and took it upon himself to continue pushing the button, believing that this was his purpose. However, Locke soon lost his faith in the Island and stopped pushing the button which ultimately caused the discharge. After this, Locke looked for his purpose again and led the mission to rescue Jack from the Others. Locke eventually decided to stay with the Others and with Sawyer’s help, he passed the test of killing his father. However, his apparent ability to commune with Jacob made John a threat to Ben, who shot him and left him for dead in the DHARMA Grave.
An apparition of Walt (possibly the Man in Black or the Island itself) found Locke and told him that he still had work to do. (This phrase was previously spoken by the MiB as Christian, hinting that he was impersonating Walt.) After Jack called the freighter for rescue, John (convinced that the freighter had no intention of helping them) led a group of his supporters to the Barracks for safety, where they were attacked by mercenaries. After the Oceanic Six left and Ben moved the Island, John assumed leadership of the Others, but was immediately separated from them as a result of the Island skipping through time. Locke left the Island via the Orchid, in an attempt to stop the erratic flashes through time and bring back everyone who left. After trying and failing to reunite them, John attempted to take his own life, only to be stopped and then strangled by Ben. His death was used to convince the others to return to the Island. John’s corpse was placed upon Ajira 316 and crashed on Hydra Island along with the plane in 2007.
After the crash, Locke appeared to have been resurrected, rejoining the Others and embarking on a mission to assassinate Jacob. However, his body was discovered in the hold of Flight 316 some days later. John Locke had been dead all along and had been replaced by The Man in Black. After several days he was finally buried in the graveyard. Jack later carried on and fulfilled Locke’s goal of protecting the Island.