The head of certain churches is known as the Pope: see [1] for complete list.
Links on Althistory Wiki
Roman Catholic Church
- List of Popes of Papal States (Washington Shot at Murdering Town!)
- List of popes (Cabotia and Brasil)
Popes and kings of Italy (Interference)
Individual popes:
- Benedict XV
- Pope John Paul II (Lauerdauch World)
- Pope Augutta (Lauerdauch World)
- John Paul II (Basil Hume)
Antipopes
In OTL there have been a number of persons designated Antipopes - who were in opposition to the Pope in Rome.
In the present era a number of Catholic figures, often of a more conservative frame of mind have declared the See of Rome vacant, and have set themselves up as Popes: they are usually known as sedevacantists, and often have a fairly minor support.
There are various althistory possibilities arising - for example the various Antipopes were recognised as the true pope. Alternatively the Antipope and Sedevacantists gain enough support to form recognisable 'breakaway Catholic churches' (as outsiders might so define them.)
Relevant Wikipedia pages are [2] for earlier antipopes and [3] for the more modern ones.