King Hassan, also known as the First Hassan, is the Grand Assassin of the Fate series and a major figure in Fate/Grand Order's Camelot storyline, where his shadowy, skull-masked presence made him an instant fan favourite. Short voice clips of his deep, imposing delivery began circulating among Fate fans and editors, who reused them to punctuate dramatic entrances and intimidating reveals. The 'Doko da' shout works well out of context because it needs no translation to sound threatening, and it appears in anime edits, gaming montages and reaction videos whenever a creator wants an entrance to feel legendary.