List of Famous people with last name I

Basil I, called the Macedonian, was a Byzantine Emperor who reigned from 867 to 886. Born a simple peasant in the theme of Macedonia, he rose in the Imperial court. He entered into the service of Theophilitzes, a relative of Emperor Michael III, and was given a fortune by the wealthy Danielis. He gained the favour of Michael III, whose mistress he married on the emperor's orders, and was proclaimed co-emperor in 866. He ordered the assassination of Michael the next year. Despite his humble origins, he showed great ability in running the affairs of state. He was the founder of the Macedonian dynasty. He was succeeded upon his death by his son Leo VI.

Richard I, also known as Richard the Fearless, was the count of Rouen from 942 to 996. Dudo of Saint-Quentin, whom Richard commissioned to write the "De moribus et actis primorum Normanniae ducum", called him a dux. However, this use of the word may have been in the context of Richard's renowned leadership in war, and not as a reference to a title of nobility. Richard either introduced feudalism into Normandy or he greatly expanded it. By the end of his reign, the most important Norman landholders held their lands in feudal tenure.

Muwatalli I was a king of the Hittites.

Dom Teodósio I of Braganza was the 5th Duke of Braganza, among other titles. He is known for ceding the title of Duke of Guimarães to Infante Duarte of Aviz, alongside some of the wealth and properties of the House of Braganza.

Hetepheres I was a Queen of Egypt during the Fourth Dynasty of Egypt.

Reccared I was Visigothic King of Hispania and Septimania. His reign marked a climactic shift in history, with the king's renunciation of Arianism in favour of Catholicism in 587.

Ermengol I (974–1010), called el de Córdoba, was the Count of Urgell from 992 to his death. He was the second son of Borrell II of Barcelona and his first wife, Letgarda. He was the second of the counts of Urgel and famous mainly for his participation in the Reconquista.

Welf I or Welfo was a Swabian nobleman. He was a member of the Elder House of Welf.