exodia the forbidden one
A duel monster from the original Yu-Gi-Oh! series. The first (and arguably most famous) "instant win" card of the franchise, which requires the user to collect all 5 cards representing his body parts (head, both arms, and both legs) in their hand, thus requiring an immense amount of luck and/or elaborate deck build to activate its effect.
Note that this tag also covers other individual "Exodia limbs", such as Left Arm of the Forbidden One or Right Leg of the Forbidden One, etc.