Reinaldo Paniagua-Diez (20 July 1934 – 29 January 2021) was a Puerto Rican politician and lawyer. He was the seventh Puerto Rico Secretary of State from 1977 to 1979. From 1985 to 1989, he was a member of the Senate. Paniagua Diez was a member of the New Progressive Party. He was born in Santurce, Puerto Rico.