Memo is a nickname, often of Guillermo. People with the nickname include:
Memo Acevedo, Colombian-born Canadian-American jazz drummer, percussionist, composer, arranger, bandleader and educator
Memo Benassi (1886–1957), Italian film actor
Memo Gidley (born 1970), Mexican-American race car driver
Guillermo Gonzalez (soccer) (born 1986), American soccer player
Guillermo Gracida Jr. (born 1956), Mexican polo player
Ángel Guillermo "Memo" Heredia Hernández (born 12 February 1975), Mexican former discus thrower and sports coach known for his involvement in the BALCO scandal
Memo Luna (born 1930), Mexican baseball player
Guillermo Ochoa (born 1985), Mexican soccer player
Mehmet Okur (born 1979), Turkish basketball player
Memo Rojas (born 1981), Mexican race car driver
Guillermo Valencia (footballer), Colombian football player and coach