Infante Ferdinand, Duke of Viseu and Beja (or Fernando, Portuguese pronunciation: [fɨɾˈnɐ̃du], 17 November 1433 – 18 September 1470) was the third son of Edward, King of Portugal and his wife Eleanor of Aragon.

When Afonso V's first daughter, Princess Joan, was born (1452), Infante Ferdinand finally lost this title.

However, his brother, King Afonso V of Portugal, as soon as he knew about Ferdinand’s escape, ordered to the Count of Odemira, which was patrolling the strait of Gibraltar with a fleet, to intercept the infante's ship and bring him back to mainland Portugal.

He was finally allowed to fight in north Africa: first in 1458 he escorted the king to the conquest of the Moroccan city of Alcácer Ceguer; and for a second time, in 1468, he led a Portuguese fleet that conquered and destroyed the port of Anfa (Anafé in Portuguese), today included in Casablanca, which was a barbary corsairs base.

He married his cousin Beatrice of Portugal (Portuguese: Beatriz) in 1447, daughter of Infante João, Lord of Reguengos (his uncle).