Guillermo León Valencia Muñoz (27 April 1909 – 4 November 1971) was a Colombian politician, lawyer and diplomat who served as the 21st President of Colombia from 1962 to 1966.

On January 31, 1931 he married Susana López Navia, a 20-year-old secretary with whom he had four children: Pedro Felipe, Alma, Ignacio, and Diana.

[5] However, four years later Valencia did accept the position and became Minister of Foreign Affairs on May 25, 1953, a post he held for the remainder of the administration of Roberto Urdaneta Arbeláez until General Rojas Pinilla took over.

In 1962, Valencia was nominated by the Colombian Conservative Party as their candidate for the presidency, facing the liberal Alfonso López Michelsen.

In matters of social reform, his administration increased the national budget for education by 20%, and under the auspices of the government of the United States, launched the construction of Ciudad Kennedy, a project of 200,000 affordable homes for lower income citizens.