Known as the Great Sage Equaling Heaven (斉天大聖, Seiten Taisei?), Sun Wukong was the disciple of Xuanzang, following her across India with his fellow disciples. During his adventures, he was punished by Shakyamuni, reaching the "edge of the world" only to find that it was Shakyamuni's palm.
He is a water god referred to as the Handsome Monkey King of the Waterfall.
Sun Wukong has fiery eyes with golden pupils.
Sun Wukong loves battle, sometimes entering a berserker state when in combat.
The Adventures of Lord El-Melloi II
Long ago, as part of a collaborative effort between Wuzhiqi, the Crudelis family of Atlas, and a mage from the Wandering Sea, Ergo devoured the flesh of three gods and imbued their factors inside himself. One of these gods was Sun Wukong, and Ergo gained Wukong's abilities.
The Man Who Devoured God
When Ergo realizes that Sun Wukong is one of the gods inside of him, Wukong appears in the middle of a lake within Ergo's mind and tells him that he is correct.
The Devil of the Wandering Sea
When Ergo is battling Bai Ruolong Wukong forcibly activates his Noble Phantasm Ruyi Jingu Bang from within Ergo, freezing Ruo in place within solidified space. Inside his mind, Ergo sees Wukong berserking in the middle of a red ocean with bursts of flame instead of waves. As he remembers Wukong's battle-crazed personality from the stories, Ergo is swallowed by the flames.
Sun Wukong briefly appears when thought of by Kohaku as an original Servant in the lead-up to the reveal of Sakura Saber, but is quickly discarded after two pages as part of a gag. Although discarded, he appears on the cover of a volume, so it is unknown if he will remain a recurring character.
Xuanzang mentions him often in Fate/Grand Order, as well as Nezha's wish being to have a rematch with him. The female Ritsuka Fujimaru dresses as Sun Wukong in the Craft Essence "The Classic Three Great Heroes".
Sun Wukong is said to be the equal of Nezha.
His Noble Phantasm is Ruyi Jingu Bang (如意金箍棒?). Before Wukong turned the Ruyi Jingu Bang into a weapon, it was a pillar holding together the bottom of the ocean. It's an item originally made to give form to what is vague. A Noble Phantasm that held a Texture in place, just like the Holy Spear Rhongomyniad. The area hit by the staff has the space around it fixed in place by Wukong's Authority, creating a solid block of air that pins the opponent in place.
The version of Sun Wukong and Ruyi Jingu Bang that appeared in The Adventures of Lord El-Melloi II were different than the version in Koha-Ace, indicating that all of Wukong's potential Noble Phantasms have likely changed as well.
In Koha-Ace, he is depicted as a Servant briefly as part of a gag for a single strip. He shows the ability to swap between a male and female form at will. His Noble Phantasms are the Ruyi Jingu Bang: Divine Rare Iron That Suppresses the Heavenly River (天河鎮定神珍鉄, Tenga Chintei Jinchintetsu?), golden chain mail shirt (鎖子黄金甲?), phoenix-feather cap (鳳翅紫金冠?), and cloud-walking boots (藕糸歩雲履?). He can use a Reality Marble-like skill that involves a process similar to Tsubame Gaeshi on a much larger scale.