The Berserker-class Servant of Gudako in the parody work Learn with Manga! FGO.

Paul Bunyan is a figure originating from American folklore. Described in the tall tales of America's pioneer era, Bunyan was the strongest lumberjack in America whose height was described as a giant so tall as to reach the clouds. Accompanied by a giant, blue male ox named "Babe", his recklessness from his large size spawned many legends.

(Source: TYPE-MOON Wiki)