A Wither Skeleton is a hostile mob found in the Nether dimension of the game Minecraft. They are tall, dark, and skeletal creatures that wield stone swords. Wither Skeletons spawn in nether fortresses and are known for their ability to inflict the Wither effect, which gradually drains health. When defeated, Wither Skeletons have a chance to drop coal, bone, or the rare Wither Skeleton skull. These skulls are essential for summoning the Wither, a powerful boss mob. Players often seek out Wither Skeletons to collect their skulls and prepare for challenging battles in the game.