ring‧lead‧er /ˈrɪŋˌliːdə $ -ər/ noun [countable]
someone who leads a group that is doing something illegal or wrong:
the ringleader of a new international drugs ring

[TahlilGaran] Dictionary of Contemporary English ▲

leader the person who directs or controls a group, organization, country etc:
12,000 party members will vote next week to elect a new leader.
leaders of developing nations from around the world
ruler someone, such as a king or queen or a military leader, who has official power over a country or area:
Sheik Mohamed, ruler of Dubai
Argentina’s former military rulers
head of state someone who leads a country or state:
Twenty-one heads of state will meet at the annual World Trade summit.
figurehead someone who is seen as the leader of a country or organization, although he or she does not have any real power:
the Queen’s role as a national figurehead
There are advantages in having a respected personality as a figurehead for the organisation.
ringleader someone who leads a group that is doing something illegal or wrong:
The alleged ringleaders of the gang have been arrested.
the ringleaders of the airplane bomb plot

[TahlilGaran] English Thesaurus ▲

ringleader
n. phr. The chief of an unsavory group; a higher-up.
The FBI finally caught up with the ringleader of the dope smugglers from South America.

[TahlilGaran] English Idioms Dictionary ▲