Carlos A. Romero Barceló was Puerto Rico's fifth popularly elected Governor, and the second to be a member of the New Progressist Party (PNP).

Nicknamed El Caballo (The Horse) Romero Barceló was governor from 1977 to 1985, beating arch rival Rafael Hernandez Colon twice during that time, but losing the third time, in the 1984 elections.

Romero Barceló brought some good economic resolutions to the island during his time, his emphasis on the island's touristic potential being a key to the improvement of the lifestyles of many Puerto Ricans. But at the same time, 3 Independist activists were murdered in 1977 at the area known as Cerro Maravilla, and most Puerto Ricans linked Barcelo to the killings.

Romero Barceló, a rabid boxing fan who helped bring many world championship bouts to San Juan during his time as Governor, won the 1980 election by the closest margin in Puerto Rican election history, beating Hernandez Colon by only 3,000 votes. Almost immediately, the Cerro Maravilla killings investigation started, and in 1983, a Cerro Maravilla trial was launched. The trial was televised every day nationally on live tv for as long as it lasted, and this greatly affected Romero Barceló's chances of winning the 1984 elections, and after it became official he had lost the election, a tv reporter asked him about his loss, and he muttered the now legendary words Que Derrota? (What loss???)

Romero Barceló ran for Puerto Rico's Resident Commissioner in Washington D.C in 1988, but Puerto Ricans decided to give their vote to Miguel Hernández Agosto of the Popular Democratic Party,(PPD), instead. This after he and Hernandez-Agosto engaged in an angry and legendary argument in front of live tv at the Ojeda Sin Limite show, where they called each other a liar. But in 1992's elections, he won the commissioner's office and moved to Washington soon after. He won it again in 1996, and returned to Puerto Rico after the 2000 elections.

Romero Barceló is married to Kate Donnelly.