Fernando de la Cerda (1275–1322)

Fernando de la Cerda (born Valladolid, 1275 – died Paris, 1322) was the eldest son of Infante Ferdinand de la Cerda and Blanche of France, and thus a grandson of King Alfonso X of Castile and King Louis IX of France.

Following the premature death of his father in 1275, Fernando, as the eldest male descendant of Alfonso X, was considered by some as the rightful heir to the throne of Castile and León. However, Alfonso X instead designated his second son, Sancho, as his heir. This decision disregarded the established custom of primogeniture, which favored Fernando de la Cerda's line.

This act of disinheritance ignited a protracted succession crisis. After Alfonso X's death in 1284, Sancho IV ascended to the throne, further marginalizing Fernando and his younger brother, Alfonso de la Cerda.

Fernando spent much of his life in exile, primarily in France, under the protection of his maternal family. He never directly challenged Sancho IV for the throne. He married Joan of Narbonne.

His descendants, known as the Cerda line, continued to lay claim to the throne of Castile for generations, and this claim intermittently factored into Castilian politics and alliances throughout the 14th century. While Fernando himself did not actively pursue the throne, his existence and his father's disinheritance served as a perpetual point of contention and instability in the kingdoms of Castile and León. His descendants continued to play a role in the power struggles of the Iberian Peninsula.