Eon (c. 400) was a king of Axum. He is primarily known through the coins minted during his reign, where his name is written in Greek as "Eon Bisi Anaaph". While "bisi Anaaph" is usually understood to mean "man of Anaaph", Richard Pankhurst notes that the scholar Stephen Wright has argued the word bisi "might well be used in relation to the King's horse in the same way that Ethiopians of much later times used the word Aba. Sahle Sellassie, for example, was often known as Aba Dina (Dina being the name of his favorite horse)."
Eon may be the same person as the King Hiuna, who is mentioned in the Book of the Himyarites as leading a military expedition from Aksum across the Red Sea into South Arabia; Munro-Hay notes that the "difference in spelling is no more than would result from transposing the name into the two languages concerned"; but he admits that the identification is not conclusive, or whether Hiuna was even a king.
Eon was the first king of Axum to use the mysterious title + BAC + CIN + BAX + ABA, which Munro-Hay reports has been interpreted to mean Basileus habasinon -- "King of the Habashat/Habash", a title used in South Arabian inscriptions to refer to the Axumite kings.