Enrique III of Portugal was a monarch who ruled from 1578 until his death in 1580. He was the last king of the Aviz dynasty and was known for his short reign, which lasted only two years. Enrique was the son of John III of Portugal and Catherine of Austria, and he ascended to the throne after the death of his cousin, Sebastian I of Portugal. His reign was marked by political instability and the struggle for succession, leading to the Portuguese succession crisis. After Enrique's death, the throne was claimed by Philip II of Spain, resulting in the Iberian Union, which united Portugal and Spain under a single crown for 60 years.