Diego Martínez de Villamayor (died 5 November 1176) was a noble of the Kingdom of Castile from the house of the counts of Bureba, who was very influential at court. He was the advisor of Alfonso VII and Sancho III, and treasurer of Alfonso VIII. Diego Martínez de Villamayor was the son of Martín Díaz of the house of Salvadores. His mother is sometimes given as María García of the house of Villamayor and sometimes as Jimena Pérez. He inherited land at Benevívere from his mother. He married María Ponce de Minerva, daughter of Ponce de Minerva and Estefanía Sánchez.