Stamina Potion

A Stamina Potion is a consumable item that fully restores a character's Stamina. In Diablo II: Lord of Destruction, it also gives the player unlimited Stamina for 30 seconds. They are dropped quite often by monsters and chests, and are sold by merchants. They are very useful for well into Nightmare difficulty as their time limit can stack and they are cheap, making buying in bulk before each trip out of town guarantee many minutes of infinite running.

A large amount of stamina potions are dropped by the Cow King in the Secret Cow Level, suggesting that perhaps the stamina potion is milk.