The Sapa Inca ("The Great Inca"), also known as Apu ("Divinity"), Inka Qhapaq ("mighty Inca"), or simply Sapa ("The Great One") was the ruler of the Kingdom of Cusco and later, the Emperor of the Inca Empire (Tawantinsuyu). The origins of the position are mythical and tied to the legendary foundation of the city of Cusco but historically it seems to have come into being around 1100. The position was hereditary, with son succeeding father.

There were two known dynasties, led by the Hanan and Hurin moieties respectively. The latter was in power at the time of Spanish conquest. The last official Sapa Inca was Atahualpa, who was executed by the Spanish in 1533, though several of successors later claimed the title.

Little is known of the rulers of the first dynasty of Sapa Incas. Evidently, they were affiliated with the Hurin moiety and their rule did not extend beyond the Kingdom of Cusco. Their origins are tied to the mythical establishment of Cusco and are shrouded in later foundation myth. The dynasty was supposedly founded by Manco Cápac, considered the son of the sun god Inti.

The Inca Empire, or Inka Empire (Quechua: Tawantinsuyu), was the largest empire in pre-Columbian America. The administrative, political and military center of the empire was located in Cusco in modern-day Peru. The Inca civilization arose from the highlands of Peru sometime in the early 13th century.

From 1438 to 1533, the Incas used a variety of methods, from conquest to peaceful assimilation, to incorporate a large portion of western South America, centered on the Andean mountain ranges, including, besides Peru, large parts of modern Ecuador, western and south central Bolivia, northwest Argentina, north and central Chile, and southern Colombia into a state comparable to the historical empires of Eurasia.

The official language of the empire was Quechua, although hundreds of local languages and dialects of Quechua were spoken. The Inca referred to their empire as Tawantinsuyu which can be translated as The Four Regions or The Four United Provinces.

There were many local forms of worship, most of them concerning local sacred "Huacas", but the Inca leadership encouraged the worship of Inti—the sun god—and imposed its sovereignty above other cults such as that of Pachamama. The Incas considered their King, the Sapa Inca, to be the "child of the sun."