Don (Spanish honorific)
Used as a title of respect for a Spanish or Latin American man, equivalent to 'Mr.' or 'Sir' in English. Often appears before a given name.
from Spanish
In Spain, older men are sometimes addressed as 'Don José' and the like.
bigwig; important person; boss
Japanese slang for a powerful or influential person, especially in business, politics, or organized groups. Often carries a nuance of authority and sometimes intimidation.
He's known as the don of the political world.
He is called the don of the industry.
That politician is a bigwig in the local area.
首領 is a formal, often legal or journalistic term for the head of a criminal or rebel group, while ドン is a more colloquial, slang-like way to call the same kind of powerful figure.
half-holiday; half-day off · sixth round (in hanafuda)
wall slam (romantic); kabedon · banging on the wall (to quieten neighbour)
floor pin; pinning someone down by lying on them · floor banging; banging on the floor to quieten a neighbor
pinning someone against a wall with a knee between their legs
ready, go! · race; competition
From Spanish 'Don', a title of respect. The slang sense developed in Japanese by extension, likening a powerful figure to a mafia don.