noun
ringleader; mastermind; leader of a plot
Refers to the person who instigates or leads a conspiracy, rebellion, or criminal scheme. Often used in historical or dramatic contexts.
事件の首魁はまだ捕まっていない。
The ringleader of the incident has not been caught yet.
彼はクーデターの首魁として知られている。
He is known as the mastermind of the coup.
noun
A less common, somewhat literary use for someone who leads the way in a field or movement. Often replaced by 先駆者 or パイオニア in modern speech.
彼は近代医学の首魁と称されることもある。
He is sometimes called a pioneer of modern medicine.