Saint Francisco Marto (1908–1919) was a Portuguese child from Aljustrel, Fátima, known for witnessing Marian apparitions alongside his sister Jacinta and cousin Lúcia dos Santos in 1917. During these events, the Virgin Mary emphasized prayer, penance, and devotion to the Rosary, profoundly influencing Francisco's spiritual life.

Following the apparitions, Francisco became deeply contemplative, often seeking solitude to pray and meditate, especially before the Blessed Sacrament. His health declined after contracting influenza, leading to his death on April 4, 1919, at the age of 10.

Recognizing their piety and the significance of the apparitions, the Catholic Church beatified Francisco and Jacinta on May 13, 2000, and later canonized them on May 13, 2017. They are among the youngest non-martyr saints in Church history.