Saint Jacinta Marto (1910–1920) was a Portuguese child from Aljustrel, Fátima, who, along with her brother Francisco and cousin Lúcia dos Santos, witnessed several apparitions of the Virgin Mary in 1917. Known for her cheerful and affectionate nature, Jacinta was deeply moved by the visions, especially a glimpse of hell, which inspired her to embrace prayer and penance for the conversion of sinners.

After the apparitions, Jacinta's commitment to the messages of Our Lady intensified; she willingly endured sacrifices and offered her sufferings for the salvation of souls. In 1918, she contracted influenza, which led to prolonged illness and eventual hospitalization in Lisbon, where she passed away on February 20, 1920, at the age of nine.

Recognizing their profound faith and the significance of the Fátima events, the Catholic Church beatified Jacinta and her brother Francisco on May 13, 2000, and later canonized them on May 13, 2017. They are among the youngest non-martyr saints in Church history.