Papantzin (fl 1509 - fl. 1525) was a Texcocoan princess, the granddaughter of Nezahualpilli, and the sister-in-law of Moctezuma II, whose policy was to marry his brothers and male relatives to the daughters of (potentially) rival kings, and thus secure his realm. Ten years later, the Spanish conquered Mexico, and Papantzin became one of the first natives to convert to Christianity. She was baptized in 1525 when the first Franciscan friars evangelized Texcoco.