A Marian apparition is a reported supernatural appearance by Mary, the mother of Jesus, or a series of related such appearances over a period of time.

In the Catholic Church, in order for a reported appearance to be classified as a Marian apparition, the person or persons who claim to see Mary (the "seers") must claim that they see her visually located in their environment. If the person claims to hear Mary but not see her, this is known as an interior locution, not an apparition. Also excluded from the category of apparitions are dreams, visions experienced in the imagination, the claimed perception of Mary in ordinarily-explainable natural phenomena, and miracles associated with Marian artwork, such as weeping statues.

Believers consider such apparitions to be real and objective interventions of divine power, rather than subjective experiences generated by the perceiving individuals, even in cases where the apparition is reportedly seen by only some, not all, of the people present at the event's location.

Marian apparitions are considered expressions of Mary's ongoing motherly care for the church. The understood purpose of each apparition is to draw attention to some aspect of the Christian message, given the needs of a particular time and place. Apparitions are often accompanied by other alleged supernatural phenomena, such as medical cures. However, such miraculous events are not considered the purpose of Marian apparitions, but are alleged to exist primarily to validate and draw attention to the message.

Françoise Mélanie Calvat (French: [fʁɑ̃swaz melani kalva], 7 November 1831 – 14 December 1904), called Mathieu, was a French Roman Catholic nun and Marian visionary. As a religious, she was called Sister Mary of the Cross. She and Maximin Giraud were the two seers of Our Lady of La Salette.