Modesto Castillo (born 24 February 1959, in La Romana, Dominican Republic) is a former sprint and hurdling athlete who specialised in the 110 metres hurdles.

Castillo represented the Dominican Republic at the 1984 Summer Olympics in Los Angeles, United States, being eliminated in the first round of the 110 metres hurdles after finishing fifth in his heat. Four years later he competed for the Dominican team at the 1988 Summer Olympics in Seoul, South Korea. He qualified from his heat in the 110 metres hurdles before being eliminated in the quarterfinals.^[1]