Gaspar de Quesada (died April 7, 1520) was a Spanish explorer who participated in Magellan's circumnavigation as captain of the Concepción, one of the expedition's five ships. Approximately six months in to the expedition, Quesada, with two other Spanish captains, attempted to overthrow Magellan in the Easter mutiny at the South American port of St. Julian. The mutiny failed and Magellan had Quesada executed.

Little is known of Quesada's life before the Magellan expedition. A letter to Manuel I of Portugal from consul Sebastião Alvares described Quesada as "a servant of the Archbishop [of Seville]".^[1] Charles I of Spain wrote that he had been "informed about his reputation and abilities".^[1]

Quesada was appointed as captain by the archbishop Juan Rodríguez de Fonseca (leader of the Casa de Contratación), along with the expedition's other two Spanish captains, Juan de Cartagena and Luis Mendoza. These three captains despised Magellan, the expedition's Portuguese captain-general, and would go on to be the architects of the Easter mutiny.^[2]

The expedition left Spain September 20, 1519, sailing west for South America. During a stop at the Canary Islands, Magellan received a secret message from his father-in-law, Diogo Barbosa, warning him that the Spanish captains were planning to mutiny. Later, during the Atlantic crossing, following the trial of a sailor caught in an act of sodomy, Magellan met with his captains to discuss their route. During the meeting, Cartagena became increasingly disrespectful to Magellan, eventually declaring he would no longer take orders from the captain-general.^[3] At this, Magellan grabbed Cartagena and declared him under arrest. In response, Cartagena called on Quesada and Mendoza to retaliate against Magellan (an incitement to mutiny). Quesada and Mendoza held back. After the confrontation, Cartagena was briefly put in stocks, but Quesada and Mendoza persuaded Magellan to release Cartagena, and allow him to be confined to the Victoria (under command of Mendoza).^[4]

The expedition landed at Rio de Janeiro December 1519, where they stayed for two weeks. After an incident in which Cartagena was allowed to leave the Victoria to come ashore (possibly to join in the orgiastic celebrations taking place with the natives, or as part of another mutiny plot), Magellan considered marooning Cartagena, but instead had him transferred into the custody of Quesada aboard the Concepción.^[5]

After leaving Rio de Janeiro in late 1519, the fleet sailed south along the coast for three months, searching for a passage around or through the continent. When the weather conditions became intolerable, the fleet anchored on March 31 at a natural harbor they called Saint Julian, located in modern-day Argentina. There they planned to wait out the winter before resuming their search for a strait.

Following the Easter mutiny, Magellan held a court martial, sentencing Quesada to death (the other surviving Spanish captain, Juan de Cartagena, was sentenced to be marooned). Unable to find a volunteer executioner, Magellan offered to commute the sentence of Quesada's squire, Luis Molino, if he would perform the duty. Molino agreed, and on April 7, 1520, Quesada was beheaded. His and Mendoza's bodies were quartered and the parts impaled and displayed on gibbets as a warning. Later, Sir Francis Drake reportedly found the gibbets when he tried and executed Thomas Doughty at St. Julian in 1578.^[7]