In Welsh mythology, Culhwch (pronounced "Kilhooch" with the "ch" as in the Scottish "loch") is a cousin of King Arthur and the protagonist of the story Culhwch and Olwen found in the Mabinogion.

Culhwch's stepmother wants him to marry her daughter but he refuses. Angry, she curses him so that he can marry no one but the beautiful Olwen. Olwen's father, Ysbaddaden, is a vicious giant who will die if his daughter marries, so he requires Culhwch to complete a number of impossible tasks. With the help of his cousin and his men, Culhwch completes the tasks and marries his love.