Follower of a number of Christian penitent sects who would ritually flagellate themselves.
The first flagellants were a sect in Perugia around 1260 and, inspired by the plague sweeping Europe in the mid-14th century, again in 1348 who would go on processions lashing themselves and calling upon bystanders to repent and join them, typically for a period of 33 and a half days. By the time the king of Naples decided that there were too many of them and that they represented a political force capable of inciting civil unrest, the practice had spread well beyond Italy. Flagellants started out as a very pious movement but later became involved in attacks on Jews in northern Europe, They were declared heretics by pope Clement VI in 1349 after the second emergence which garnered a popular following that was perceived to be a threat to the Vatican's authority.
German Flagellant sects in the late 14th century rejected church doctrine and became ascetic chiliasts. Despite their condemnation by the Council of Constance in 1417, they would persist until the end of the 15th century.
Flagellant sects would survive in Spain and emerged again in the New World, the last reported ones being among christianised Native Americans, Los Hermanos Penitentes, in New Mexico as late as the end of the 19th century. The practice today is now sporadic and confined to individual expressions of penitence.