Antipopes
Groups sometimes form around antipopes, who claim the Pontificate without being canonically and properly elected to it.
Traditionally, this term was reserved for claimants with a significant following of cardinals or other clergy. The existence of an antipope is usually due either to doctrinal controversy within the Church (heresy) or to confusion as to who is the legitimate pope at the time (see schism). Briefly in the 15th century, three separate lines of popes claimed authenticity (see Papal Schism). Even Catholics don't all agree whether certain historical figures were popes or antipopes. Though antipope movements were significant at one time, they are now overwhelmingly minor fringe causes.
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