Sancho IV "the Brave" (1257/58 – April 25, 1295) was a king of Castile and León (1284 - 1295). He was the second son of Alfonso X and Violant of Aragon princess of Aragon and daughter of James I of Aragon the Conqueror. His elder brother, Ferdinand de la Cerda, died in November 1275, and in 1282 Sancho assembled a coalition of nobles to declare for him against Ferdinand's son Alfonso, then took control of the kingdom when Alfonso X died in 1284.

Sancho IV married Maria de Molina in 1282 and they had the following children:
• Isabella (1283-1328). Married and divorced James II of Aragon.
• Ferdinand IV (1285-1312).
• Alfonso (1286-1291)
• Enrique (1288-1299)
• Pedro (1290-1319). Married Maria of Aragon, daughter of James II of Aragon. Their daughter, Blanca of Castile, married and later divorced Peter I of Portugal.
• Felipe (1292-1327). Married his cousin Margarita de la Cerda, daughter of Alfonso de la Cerda.
• Beatrice (1293-1359). Married Afonso IV of Portugal.

In 1291, Sancho led an expedition that captured the port of Tarifa from the Moors and his uncle don Juan.

Just before succumbing to a fatal illness, he appointed his queen Maria de Molina to act as regent for his 9 year old son Ferdinand IV of Castile and Leon. He died in 1295 in Toledo.