A five-star rank is the highest military rank in many countries. The rank is that of the most senior operational military commanders, and within NATO's standard rank scale it is designated by the code OF-10. Not all armed forces have such a rank, and in those that do the actual insignia of the five-star ranks may not contain five stars. For example: the insignia for the French OF-10 rank maréchal de France contains seven stars; the insignia for the Portuguese marechal contains four gold stars. The stars used on the rank insignias of various Commonwealth of Nations are sometimes referred to colloquially as pips, but are stars of the orders of the Garter, Thistle or Bath or Eversleigh stars depending on the wearer's original regiment or corps, and are used in combination with other heraldic items, such as batons, crowns, swords or maple leaves.

Typically, five-star officers hold the rank of general of the army, admiral of the fleet, field marshal, marshal or general of the air force, and several other similarly named ranks. As an active rank, the position exists only in a minority of countries and is usually held by only a very few officers during wartime. In times of peace, it is usually held only as an honorary rank. Traditionally, five-star ranks are granted to distinguished military commanders for notable wartime victories and/or in recognition of a record of achievement during the officer's career, whether in peace or in war. Alternatively, a five-star rank (or even higher ranks) may be assumed by heads of state in their capacities as commanders-in-chief of their nation's armed forces.

Despite the rarity and seniority of five-star officers, an even more-senior rank of general of the armies was adopted in the United States. Other names for highly senior ranks from the twentieth century include généralissime (France), generalísimo (Spain) and generalissimus (USSR).