The Siege of Zara or Siege of Zadar (Croatian: Opsada Zadra) (November 10-November 23, 1202) is the first major action of the Fourth Crusade and the first attack against a Catholic city by Catholic crusaders.

The Fourth Crusade sacks the Croatian town of Zadar, a rival of Venice, despite letters from Pope Innocent III forbidding such an action and threatening excommunication.