Ivaylo (died 1281), also spelled Ivailo (), was a rebel leader who ruled briefly as tsar of Bulgaria. In 1277, he spearheaded a peasant uprising and forced the Bulgarian nobility to accept him as emperor. He reigned as emperor from 1278 to 1279, scoring victories against the Byzantines and the Mongols. Beset by foreign and domestic enemies, which included the Bulgarian nobles, he was eventually forced into exile among the Mongols, where he presented himself as a dethroned vassal. The Mongols then killed him in 1281 as an enemy of the Byzantine emperor Michael VIII Palaeologus.