Dom Fernando I of Braganza (Portuguese pronunciation: [fɨɾˈnɐ̃du]; 1403 – 1 April 1478) was the 2nd Duke of Braganza and the 1st Marquis of Vila Viçosa, among other titles. He took part in the Portuguese conquests in North Africa and served as governor of different territories there.

Born in 1403, Fernando I was the son of Afonso, 1st Duke of Braganza and Beatriz Pereira de Alvim. When still a child, he received the title of 3rd Count of Arraiolos from his grandfather Nuno Alvares Pereira.

In 1432, young Fernando I was called upon by King John I of Portugal for consultation on a project, promoted by the King's son, Prince Henry the Navigator, to launch a campaign of conquest against the Marinid sultanate^{[check spelling]} of Morocco. Fernando advised against the project. When the project was raised again during the reign of King Edward of Portugal in 1436, Fernando reiterated his objections. Nonetheless, despite his opposition, King Edward appointed him as constable of the nobles for the 1437 expedition to seize Tangier.^[1] Although the expedition was under the overall command of his brother Prince Henry, King Edward felt that Fernando's military expertise was necessary to make up for his brother's inexperience.

After failing to conquer the city by assault, the Portuguese expeditionary army was surrounded and starved into submission by a Moroccan relief army. In return for being allowed to withdraw his troops unmolested, Henry agreed to a treaty to deliver Ceuta back to the Marinids. For the fulfillment of the treaty, Prince Henry handed over his own brother, Ferdinand the Saint Prince, as a hostage to the Moroccans.

Back in Portugal, Fernando I led the opposition to this treaty. At the Cortes of Leiria assembled by King Edward early in 1438, he rallied the nobles and took to the floor, urging them to refuse the surrender of Ceuta back to the Marinids. He claimed that the treaty was signed under duress and invalid. It was largely because of Fernando's energetic campaign that the Cortes rejected ratification and made known to the King to find some other way of securing his brother Prince Ferdinand's release (none was found – Ferdinand the Saint Prince would die in Moroccan captivity in 1443).

Fernando I was nominated Governor of Ceuta from 1445 until 1450.^[1]

By royal decree dated from 25 May 1455, King Afonso V of Portugal granted Fernando I the new title of 1st Marquis of Vila Viçosa.

In 1458, Fernando I took part, along with his sons, in the expedition that conquered the Moroccan city of Alcácer Ceguer.

In 1460, as his older brother, Afonso, Marquis of Valença, died without legitimate issue, Fernando I became the 5th Count of Ourém and the House of Braganza's heir.^[1] One year later, following the death of his father in 1461, he also became the 2nd Duke of Braganza, 9th Count of Barcelos, 3rd Count of Neiva, and 3rd Count of Faria. He then established his seat at the primitive Castle of Vila Viçosa.

In 1471, when King Afonso V took to North Africa to conquer the city of Arzila, Fernando I remained in mainland Portugal as regent of the kingdom.

Fernando I married on 28 December 1429, Joana de Castro [pt], Lady of Cadaval (1410 – 14 February 1479). They had nine children, of whom three were stillborn.

• Marquis of Vila Viçosa
• Count of Neiva