A patriarch is a male leader. Your father might be the patriarch of your family, but your kid brother could be the patriarch of his club house.
You can trace patriarch back to its ancient Greek root pater meaning "father." What do you think a female leader is called? You got it — matriarch. Although the noun patriarch specifically refers to a male head of the family, it can more generally refer to any older, respected male. In terms of the Old Testament, patriarch refers to the men considered to be the fathers of the human race, including Jacob and Isaac.