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.
As maximum stamina increases whenever a character levels up or invests attribute points into Vitality, stamina potions generally become unnecessary as players reach higher levels.
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.
Diablo I
Recovery — Healing Potions • Mana Potions
Elixirs — Elixir of Strength • Elixir of Vitality • Elixir of Magic • Elixir of Dexterity
Quest Potions — Golden Elixir • Spectral Elixir
Demo only elixirs — Elixir of Clumsiness • Elixir of Disillusion • Elixir of Weakness
Diablo II
Recovery — Healing Potions • Mana Potions • Rejuvenation Potions • Antidote Potion • Thawing Potion • Stamina Potion
Throwing — Poison Potions • Fire Potions
Quest Potions — Potion of Life • Malah's Potion
Diablo III
Recovery — Health Potions