Celtic Guardian, known as Elf Swordsman in the Japanese version, is a character version of the card, "Celtic Guardian".
Celtic Guardian appears in the video game, Yu-Gi-Oh! World Championship 2007. He appears as a Level Three Limited Duelist, who challenges the player not to use monsters with an ATK/DEF of 1500 or more. By beating him, the player gets closer to unlocking Level Four Limited Duelists and a new Booster Pack.
In World Championship 2007, Celtic Guardian plays a Beatdown Deck titled, "Under 1500".