Gandof is a non-player character in Final Fantasy X. He is a summoner and one of the five summoners who defeated Sin using the Final Aeon 400 years before the story in Final Fantasy X. Statues of high summoner Gandof, as he was later known, can be seen in the temples of Yevon.
Gandof helped the people of Spira by sealing up the Qactuar roaming about the Thunder Plains in stone as he believed that defeating Sin was not the only thing summoners could do to help Spira. During his final battle with Sin, Gandof left his mark with the formation of a huge rift in Calm Lands known as "the Scar". This event isolated the Remiem Temple, and started the Second Calm. Gandof's sacrifice lent credence to Yevon's teachings, and doubts about the Temples subsided.
As before, the Calm was short-lived and Yu Yevon rebuilt Sin which started its rampage again as the third Sin appeared publicly with Gandof's Final Aeon as its core. Gandof was posthumously titled "high summoner", a title which would from then on be bestowed on all who had defeated Sin. Statues of Gandof were placed in Spira's temples and his story was told to all Spirans as an example of honor and sacrifice to be followed.