Gutierre Fernández de Castro (flourished 1124–66) was a nobleman and military commander from the Kingdom of Castile. His career in royal service corresponds exactly with the reigns of Alfonso VII (1126–57) and his son Sancho III (1157–58). He served Alfonso as a courtier after 1134 and as majordomo (1135–38). He was the guardian and tutor the young Sancho III from 1145. Before his death he was also briefly the guardian of Sancho's infant son, Alfonso VIII.
Gutierre took part in several military campaigns of reconquest against the Almoravid Emirate to the south of Castile. In 1139, on the king's orders, he began the successful Siege of Oreja. More often he was occupied defending the eastern frontier from invasion by Aragon or Navarre, and for this purpose the king invested him with many royal fiefs in this region. Towards the end of his life Gutierre was the elder statesman of the Castro family, and he died before his family's rivalry with the Laras developed into open civil war early in the reign of Alfonso VIII. Despite his high standing at court and his illustrious military career, Gutierre was never promoted to the rank of a count, which was the highest title borne by the Castilian aristocracy in the twelfth century.
Gutierre, who could not have been born much earlier than 1100, was the eldest son of Fernando García de Hita and his first wife, Tegridia, sister of aunt of Count Rodrigo Fernández and relative of the powerful Count Pedro Ansúrez. He had one full brother, Rodrigo Fernández. Gutierre was probably the elder brother. After 1125 their father, Fernando, disappears from the record. Although his death is not recorded, his sons went without him to make their submission to the new king, Alfonso VII, in 1126, after the death of Queen Urraca. According to the Chronica Adefonsi imperatoris ("Chronicle of the Emperor Alfonso"), a contemporary history of Alfonso's reign, Gutierre and Rodrigo were accompanied not by their father, but by their uncle, García Garcés de Aza. Although some authors have suggested that Gutierre was an upstart, both he and his brother obtained advantageous marriages to daughters of the highest nobility years before rising to prominence at the royal court and were evidently considered high-born.