Titan, the Rock Spirit is a Duel Monster Spirit of the card, "The Rock Spirit".
Titan appears in the desert arc to duel Jesse Anderson, being summoned by the Yubel-possessed Marcel Bonaparte. He materialized in the desert to duel Jesse Anderson. When he is defeated, he retreats, only to send an army of Scorpions after Jaden Yuki, Jesse, Axel Brodie, Jim Crocodile Cook and Adrian Gecko into the submarine. He is crushed by the submarine after Jaden Summons "Elemental Hero Grand Neos" to lift it from beneath the desert.
Titan plays a Scorpion Deck, used mostly to Summon Duel Spirit Monsters that pursue his targets in the real world. In Duels, he relies entirely on his "Sand Doodlebug" card, abusing its synergy with the natural "Wasteland" environment to win.