ringleader - Someone who is the main influence or motivator behind a particular action or event, especially a disruptive or controversial one.
The police managed to arrest the ringleader of the gang, who had coordinated the series of robberies across the city.
conformist - A person who behaves in accordance with prevailing standards or customs, rather than doing things that are different or original.
The hippies attracted people who didn't want to be conformists to the regular society, but actually they were becoming conformists to the hippie way of life.