The Minié ball or Minie ball, is a type of hollow-based bullet designed by Claude-Étienne Minié, inventor of the French Minié rifle, for muzzle-loading rifled muskets. It was invented in 1846 and came to prominence during the Crimean War and the American Civil War, where it was found to inflict significantly more serious wounds than earlier round musket balls. Both the American Springfield Model 1861 and the British Pattern 1853 Enfield rifled muskets, the most common weapons used during the American Civil War, used the Minié ball.

The Minié rifle was an important infantry rifle of the mid-19th century. A version was adopted in 1849 following the invention of the Minié ball in 1847 by the French Army captain Claude-Étienne Minié of the Chasseurs d'Orléans and Henri-Gustave Delvigne. The bullet was designed to allow rapid muzzle loading of rifles and was an innovation that brought about the widespread use of the rifle as the main battlefield weapon for individual soldiers. The French adopted it following difficulties encountered by the French army in North Africa, where their muskets were overtaken in range by long-barreled weapons which were handcrafted by their Algerian opponents. The Minié rifle belonged to the category of rifled muskets.