Fray Marcos de Niza (c. 1495 – March 25, 1558) was a Franciscan friar. He is credited with being the first European in what is now the State of Arizona in the United States.
He emigrated to America in 1531 for exploration of new land, and after serving his order zealously in Peru and Guatemala, de Niza was chosen to explore the country north of Sonora, whose wealth was depicted in the accounts of Álvar Núñez Cabeza de Vaca. In 1537 he arrived in Mexico City at the request of the viceroy Antonio de Mendoza. Preceded by Estevanico, the Moroccan-Berber companion of Cabeza de Vaca in his wanderings and the Black Mexican of Zuni traditions, Fray Marcos left Culiacán in March 1539, crossed south-eastern Arizona near the present-day Lochiel, penetrated to the Zuni or the Seven Cities of Cibola, and in September returned to Culiacán. He saw Cibola only from a distance, and his description of it as equal in size to Mexico City was probably exact; but he embodied much mere hearsay in his report, Descubrimiento de las siete ciudades, which led Francisco Vázquez de Coronado to make his famous expedition next year to Zuni Pueblo, in present-day New Mexico, of which Fray Marcos was the guide; and the realities proved a great disappointment.
Fray Marcos was made provincial superior of his order for Mexico before the second trip to Zuni, and returned in 1541 to the capital, in shame, where for a time was able to exercise the highest office of the Franciscans, in the province.