Juan de Salazar y Espinosa (1508–1560) was a Spanish explorer, founder of the Paraguayan city of Asunción.

Born in the city of Espinosa de los Monteros in Burgos, Spain, not much is known about his early life.

He managed to find another member of Ayolas' party, Domingo Martínez de Irala, holed up in the Puerto de la Candelaria, which was founded by Ayolas earlier in February 1537.

While continuing his trip in the search of Ayolas, he founded a fort on the eastern banks of the Paraguay River which he named "Our Lady of Asunción", due to coincidence of that day, August 15, being the Christian celebration of the Assumption of Mary.

He then traveled as far as San Pedro to look for Ayolas, only to find that he had been killed by the Chaco Indians.