Ignacio Molarja, or known in the Jesuit dictionaries as Ignacio Molarsa (Caller, Cerdeña, Italy, 1610 – Tecoripa, Sonora, Mexico, 24 November 1658) was an explorer and Jesuit missionary pertaining to the Society of Jesus of the Province of Nueva España.[1][2] The surname of the Italian Jesuit varies according to the diversity of the biographical writings on him, varying between "Molar Ja", "Molarja", "Molargia", "Molarsa", and "Molarza".[3][4] He has also been confused by contemporary dictionaries with Jerónimo de la Canal, who was one of his coworkers at the mission. Ignacio Molarja began his Catholic studies in 1635, and arrived in northwest New Spain in 1644. As an explorer, missionary and evangelizer, he founded several missions in what is today the state of Sonora, Mexico. He died due to health problems in 1658 in Tecoripa, La Colorada Municipality, Sonora.