Hilario Gelbolingo Davide Jr. GCSS KGCR (born December 20, 1935) is a Filipino lawyer, professor, diplomat, constitutionalist and former politician, who served as the 20th chief justice of the Supreme Court of the Philippines and Permanent Representative of the Permanent Mission of the Republic of the Philippines to the United Nations. As constitutionalist, Davide led the creation of the Legislative branch, and also wrote the most resolutions and the bulk of the 1987 Constitution of the Philippines, becoming its father and primary author.

The sixth of seven siblings, Davide was born in Barangay Colawin, in Argao, Cebu to Hilario Panerio Davide Sr. (1904–2006), a retired Schools Division Superintendent, and Josefa Lopez Gelbolingo, a former public school teacher. Davide Sr. though lacking in funds ensured all his children finished college. The children were disciplined from the beginning, and the boys had to learn how to gather tubo (sugarcane). The young dodong (boy) Jun enjoyed riding on a sledge harnessed by a carabao to gather tubo. No leisure was allowed until schoolwork and house chores were completed. He completed his primary education at Argao Central Elementary School and secondary education at Abellana Vocational High School. In college, he went to the country's premier state university, the University of the Philippines Diliman, Quezon City where he earned his Associate in Arts in 1955, his Bachelor of Science in Jurisprudence in 1958, and his Bachelor of Laws degree in 1959. In his first year of law he joined the honor society, "Order of the Purple Feather", then in his last year was a member of two honor societies called Phi Kappa Phi and Pi Gamma Mu. In addition, Davide edited for the school journal, the Philippine Law Journal. He took and passed the bar examinations given that same year.

From 1959 to 1963, Davide worked as private secretary to the vice-governor and later governor of the province of Cebu.

From 1962 to 1968, he was a faculty member of the College of Law of Southwestern University in Cebu City. This university, three decades later, would confer on him a degree of Doctor of Laws (Honoris Causa) in 1999.

Davide's first opportunity to get into the national scene was when he was elected as Delegate of the 4th District of Cebu to the 1971 Constitutional Convention (CONCON). He became Chairman of the Committee on Duties and Obligations of Citizens and Ethics of Public Officials. He was among three delegates who introduced the most number of reform proposals. The reforms adopted under the Constitutional Convention were, however, short-lived. Public unrest over deteriorating economic conditions and the suppression of political rights, as well as the desire of then-President Ferdinand Marcos to perpetuate himself in power, heralded the declaration of martial law in 1972.

In 1978, he was elected assemblyman for Cebu in the Interim Batasang Pambansa under the opposition party Pusyon Bisaya and became one of martial law's staunch critics. As an oppositionist in the ruling party-dominated legislative body, he was its first Minority Floor Leader. He filed the most number of bills of national significance, as well as resolutions to lift martial law. He also sought legislative investigations of graft and corruption in government and reported violations of human rights.

After the overthrow of the Marcos regime through the People Power revolt in February 1986, then-President Corazon C. Aquino convened the Philippine Constitutional Commission of 1986 and appointed Davide as one of its 50 Commissioners. He led the legislative branch article as chairman and filed the most resolutions including Resolution No. 9 which added legislative approval on martial law and a limited period on its validity, an impact which is still felt today.

In February 1988, President Aquino appointed Davide as Chairman of the Commission on Elections (COMELEC). He was the principal sponsor of the COMELEC's Rules of Procedure.