Alonso del Castillo Maldonado (?-?) was a Spanish explorer. The son of impoverished nobility, Castillo decided to make his fortune in New Spain. He joined the Pánfilo de Narváez expedition as captain in Florida in 1527. The expedition was a disaster, and only four members, Castillo, Andrés Dorantes de Carranza, Dorantes' slave, Estevánico, and Álvar Núñez Cabeza de Vaca survived a disastrous hurricane at the end. They walked across the deserts of modern Mexico, New Mexico, and Texas, before finally reaching civilization in 1536. Castillo was a deeply pious man, and is credited with faith-healing to the Native American groups the survivors encountered.
Castillo opted to stay in New Spain and make his fortune, holding one or two government positions. His final appearance in the written record is 1547. The date of his death is unrecorded.
In 1532, Alonso del Castillo Maldonado, Andrés Dorantes de Carranza, Dorantes' Moorish slave, Estevánico, and Álvar Núñez Cabeza de Vaca, were the last survivors of the Pánfilo de Narváez expedition. They had no choice but to cross Mexico on foot. One day, the group came to a crossroads. When a debate arose as to which route they should take, Estevánico put on a pair of spectacles, and selected the path favored by Cabeza de Vaca. He explained to the others how he'd found the eyewear on guard duty two nights prior, and that the eyewear could give the wear clues as to the best course of action. The other three wore it in turn, and were amazed and concerned by the device. While Castillo worried that the eyewear might be a trick of the Devil's, Cabeza de Vaca disagreed, pointing out that Satan wouldn't need to go to such lengths. However, Dorantes decided that Estevánico should use the eyewear exclusively, on the off-chance they were somehow a Satanic trap.
They continued on. While they were on the correct path, they couldn't move very fast. They frequently came to Native villages, where, thanks to the eyewear, they had success as healers. The Spaniards also preached Christianity to the natives. With Estevánico as their "compass", they made contact with Spanish soldiers in New Spain, near Culiacán, in 1636. Upon their contact with the Spanish, the group tacitly agreed to say nothing of the eyewear. The group then made their way to Mexico City. Castillo never saw Estevánico again.