What it means
A ringleader is the one steering the chaos, the main instigator who cooks up the dodgy plan and gets the rest to pile in. Could be the kid running a school prank, could be the one directing a gang. When the mess hits the fan, that's usually the person everyone points at first.
Usage examples
"The teacher knew exactly who the ringleader was, the rest just followed."
"Police arrested the ringleader but the rest of the gang scattered."
"Everyone knew Tyler was the ringleader, the others were just tagging along for the mayhem."
"She never throws the first punch, but she's always the ringleader when the group starts acting feral."
Where it comes from
Recorded in English since the 1500s, ringleader comes from ring, which could mean a circle or organised band of people, plus leader. It first took hold for the person heading a rebellious or troublesome group, so the word has long carried that whiff of being the chief trouble-stirrer.
