founder of a sect; originator; apostle
Primarily used for the founder of a religious sect or school of thought. Can also refer to the originator of a movement or invention, but less common than 創始者 or 創設者 in secular contexts.
He is known as the founder of that new religious sect.
The originator of this philosophy is an ancient Greek thinker.
開祖 specifically means the founder of a religious sect, school of thought, or martial art, whereas 元祖 is broader and also used for the first version of a product or dish.
Compound of 開 (kai, 'open, start') and 祖 (so, 'ancestor, founder'). The combination directly conveys the idea of a founding ancestor who opens a new tradition.