A patron saint is a saint who is regarded as the intercessor and advocate in heaven of a nation, place, craft, activity, class, clan, family, or person. Patron saints, because they have already transcended to the metaphysical, are believed to be able to intercede effectively for the needs of their special charges.

Saints often become the Patron saints of places where they were born or had been active. However, there were cases in Medieval Europe where a city which grew to prominence and transferred to its cathedral the remains of a famous saint who had lived and was buried elsewhere, and made him or her the city's Patron saint - such a practice conferring considerable prestige on the city concerned. In Latin America, Spanish and Portugese explorers often named location for the Saint on whose day the place was first visited - that Saint naturally becoming the Patron saint of a town or city which developed there.

Professions sometimes get a Patron saint who was himself or herself involved in that profession. Lacking such a saint, a profession would get a saint whose conspicuous acts or miracles in some way recall the profession. For example, when the hitherto unknown profession of photography appeared in the 19th Century and needed a Patron saint, this role was assigned to Saint Veronica. According to Christian tradition, Veronica gave Jesus her veil to wipe his forehead as he was being taken to Golgotha and the image of his face became miraculously impressed upon it.