pontiff

Short definition from Wiktionary

Noun

1. 1
   A member of the most illustrious of the colleges of priests of the Roman religion, the College of Pontiffs; a pontifex.
2. 2
   A bishop of the early Church; now specifically, the Pope.
3. 3
   Any chief figure or leader of a religion.

Proper noun

1. 1
   A surname transferred from the nickname.