Antonio de Ulloa (January 12, 1716 - July 3, 1795) was a Spanish general, explorer, author, astronomer, colonial administrator and the first Spanish governor of Louisiana.

Ulloa was born in Seville, the son of an economist. In 1735 he went to Peru with fellow Spaniard Jorge Juan as part of the French expedition led by Pierre Bouguer to measure an arc of the meridian. He remained there from 1736 to 1744, during which time the two Spaniards discovered the element platinum. On his return he published an account of the people and the country (1748), which was translated into English as A Voyage to South America.

In 1758 he returned to South America as governor of Huancavelica in Peru and the general manager of the quicksilver mines there. He held this position until 1764.

He arrived on March 5 1766 in New Orleans to serve as the first Spanish governor of Louisiana. The French colonists refused to recognize Spanish rule, and de Ulloa was expelled from Louisiana by a Creole uprising in 1768. For the remainder of his life he served as a naval officer and died at Isla de Leon, Cádiz.

His name is also recalled as the meterological term Ulloa's halo (also known as Bouguer's halo) which an observer may see infrequently in fog when sun breaks through (for example, on a mountain) and looks down-sun -- effectively a "fog-bow" (as opposed to a "rain-bow"). An infrequently observed meteorological phenomenon; a faint white, circular arc or complete ring of light that has a radius of 39 degrees and is centered on the antisolar point. When observed, it is usually in the form of a separate outer ring around an anticorona. Reference: Tricker, R. A. R., 1970: An Introduction to Meteorological Optics, pages 192–193.