Samuel Fritz, Czech Jesuit missionary to South America (d. 1725?)
Samuel Fritz SJ (9 April 1654 – 20 March 1725, 1728 or 1730) was a Czech Jesuit missionary, noted for his exploration of the Amazon River and its basin. He spent most of his life preaching to Indigenous communities in the western Amazon region, including the Omaguas, the Yurimaguas, the Aisuare, the Ibanomas, and the Ticunas. In 1707 he produced the first accurate map of the Amazon River, establishing as its source the Marañón.

Adept in technical arts and handicrafts, he also was a physician, a painter, a carpenter, a joiner and a linguist skilled at interacting with the Indians. He was effective and respected, and helpful to the Viceroyalty of Peru in its boundary dispute with the State of Brazil.

Between 1686 and 1715, he founded thirty-eight missions along the length of the Amazon River, in the country between the Rio Napo and Rio Negro, that were called the Omagua Missions. The most important of these were Nuestra Señora de las Nieves de Yurimaguas, and San Joaquín de Omaguas, which was founded in the first years of Fritz's missionary activities and then moved in January 1695 to the mouth of the Ampiyacu river, near the modern-day town of Pebas in the Peruvian Department of Loreto. These missions were continually attacked by the Brazilian Bandeirantes beginning in the 1690s.Fritz detailed his early missionary activity among the Omagua people in a set of personal diaries written between 1689 and 1723. Lengthy passages from these diaries were compiled and interspersed with commentary by an anonymous author in the time between Fritz's death and 1738, when they appear in the collection of Pablo Maroni.