(For other uses, see Diego (disambiguation).) Diego is a Spanish masculine given name.It derives from a re-analysis of Sant Yago ("Saint Jacob"), viz. in reference to Saint James the Greater, re-analysed as San Diego. In today's Spanish-speaking countries, Diego and Santiago are common as given names; Diego, Santiago and Sandiego are found as surnames. The forms Tiago, Thiago, Diago and Diogo are seen mostly in Portuguese speaking (Lusophone) countries.