the person in a group of offenders who carries out the main part of a criminal act. If there is more than one principal offender, they are called joint principals.

desperado (noun)

old-fashioned an extremely dangerous and violent criminal

first offender (noun)

someone who has committed their first crime

juvenile delinquent (noun)

a young person who has committed a crime or who behaves like a criminal

law-breaker (noun)

someone who commits a crime

lowlife (noun)

informal a bad person, especially a criminal

miscreant (noun)

literary someone who does something wrong or commits a crime

outlaw (noun)

old-fashioned a criminal, especially one who moves from place to place to avoid being caught

probationer (noun)

someone who has been put on probation for committing a crime

recidivist (noun)

very formal someone who continues to commit crimes or behave badly even after being punished

tsotsi (noun)

South Africaninformal a criminal, often one who comes from a black township

undesirable (noun)

someone who is thought to be dangerous or involved in crime