A golden goblet that is the ultimate prize of the Holy Grail Wars in the Fate series. It is capable of granting the victor's wish. It was corrupted by Angra Mainyu during the third Holy Grail War, which would distort any wish made upon it in the two future Holy Grail Wars to be the destruction of the world.
In Fate/Grand Order, there are several instance where multiple Holy Grails were used by the main antagonists to fulfil their plans. The player were tasked to retrieve the Grail by defeating the antagonists, thus the Holy Grails are earned after completing a major story arc or in some events. They can then be consumed to perform Palingenesis, a gameplay mechanic that increases a Servant's maximum combat level, up to level 120. This is an optional mechanic that players can utilize, so illustrations depicting FGO Servants with a Grail tend to demonstrate that the artist boosted them in their own games.