Sancho I may refer to:
Sancho I of Gascony (died 812), Basque Duke Sancho I of Pamplona (circa 860–925), Navarrese monarch Sancho I Ordóñez (circa 895–929), King of Galicia Sancho I of León (died 966), two-time King of León Sancho I of Aragon (c. 1042 – 4 June 1094), second king of Aragon Sancho I of Astarac (fl. 1050–1096/1119), count of Astarac Sancho I of Portugal (1154–1212), King of Portugal