Juan Fernández (c. 1536 – c. 1604) was a Spanish explorer and navigator in the Pacific regions of the Viceroyalty of Peru and Captaincy General of Chile west of colonial South America. He is best known for the discovery of a fast maritime route from Callao ( Peru) to Valparaíso ( Chile), as well as for the discovery of the Juan Fernández Islands off the coast of Chile.
In 1574 he discovered an alternative maritime route between Callao and Valparaíso, much faster than the old route which bordered the coastline. By taking a detour west from the coast, he managed to avoid the northernly Humboldt Current which used to slow down ships sailing south along the coast. In doing so, he discovered the Juan Fernández Islands archipelago, located west of present-day Valparaíso in the southeastern Pacific Ocean. He also discovered the Pacific islands of San Félix and San Ambrosio in 1574.
Early historians such as Alexander Dalrymple and James Burney claim that Juan Fernández was the first European to reach New Zealand. In 1575 the governor of Cuyo, Juan Jufré, organized an expedition to Terra Australis under the command of Juan Fernandez. The expedition was authorized by the governor of Chile but not the Viceroy of Peru. As a result, Jufré changed the official itinerary and pretended his expedition would only sail to the islands discovered by Fernández in 1574. In fact, the real destination of the expedition was still Terra Australis. Soon Juan Fernandez set sail from Valparaíso. After heading west for one month along the 40th parallel south, in the spring of 1576 they arrived in an island described as "mountainous, fertile, with strong-flowing rivers, inhabited by white peoples, and with all the fruits necessary to live". 
Later, the expedition set sail back for Chile and Juan Fernández wished to convey his discovery to government officials. However, Juan Jufré refused. He requested that the discovery be kept a secret as the expedition had not been authorized by the Viceroy of Peru. Later, after Jufré's death in 1578, Fernández finally shared the discovery with the authorities and tried to convince them of the need to return to the islands and establish a colony. The idea was scrapped due to lack of interest. A record exists in the Spanish Admiralty libraries which describes this discovery. It was reviewed in the 19th century by the Chilean biographer José Toribio Medina who is one of the main sources for the claim in South American literature. 
Mainstream historians do not however accept these claims. University of Auckland history professor James Belich said that similar claims that the French and Chinese discovered New Zealand prior to Abel Tasman in 1642 have also been put forward. "I think there are a number of theories of this kind and all are highly unlikely.". 
In the opinion of another University of Auckland professor, Phyllis Herda, despite the short duration of the trip between Chile and New Zealand (one month, according to Spanish records) Juan Fernández was known to be a brilliant navigator. In 1574 he discovered the much faster route between Peru and Chile and was since known as the brujo del Pacífico or "wizard of the Pacific". 
- Theory of the Portuguese discovery of Australia
- Cristóvão de Mendonça
- Explorers of the Pacific
- Explorers of Oceania
- Esparza, Jose Javier (2008). España Epica. Editorial Altera 2005. ISBN 9788496840393.
- José Toribio Medina, El Piloto Juan Fernández, Santiago de Chile, 1918, reprinted by Gabriela Mistral, 1974, pp. 136, 246; Isidoro Vázquez de Acuña, "El general Juan Jufré pionero de la navegación chilena hacia el otro lado de la Cuenca del Pacífico (1575)", Derroteros de la Mar del Sur, año 12, num.12, 2005, at: derroteros.perucultural.org.pe/art12k.htm
- Squires, Nick (2007-03-21). "Portuguese visited New Zealand '250 years before Cook'". New Zealand Herald. Retrieved 2007-03-22.
- See J. L. Arias, Memoir recommending to the king the conversion of the new discovered islands (in Spanish, 1609; Eng. trans., 1773); Ulloa, Relation del Viaje, bk. ii. ch. iv.; Alexander Dalrymple, An Historical Collection of the several Voyages and Discoveries in the South Pacific Ocean (London, 1769-1771); Freville, Voyages de la Mer du Sud par les Espagnols.
- Síntesis sobre algunos navegantes españoles transpacíficos, relacionados con el Reyno de Chile, Liga Maritima de Chile (in Spanish)
- Hooken, T. M. (1894). Some Account of the Earliest Literature and Maps relating to New Zealand, Transactions of the Royal Society of New Zealand, Volume 27, Article 71, 616-634.