an unscrupulous and ruthless subordinate, esp. a criminal

The leader of the gang went everywhere accompanied by his henchmen.

an unscrupulous supporter or adherent of a political figure or cause, esp. one motivated by the hope of personal gain

Hitler and his henchmen.

a trusted attendant, supporter, or follower.

Obsolete . a squire or page.

noun

abettor , accessory , accomplice , adherent , adjunct , aide , ally , appointee , apprentice , assistant , attendant , backer , backup * , bodyguard , coadjutant , coadjutor , cohort , collaborator , colleague , companion , deputy , fellow worker , flunky , friend , gal friday * , girl friday * , gofer * , hanger-on , hatchet man/woman , help , helper , helpmate , lackey , man friday * , partner , right-hand man/woman , right-hand person , secretary , servant , sidekick * , stooge * , subordinate , supporter , yes-person * , disciple , minion , partisan , satellite , criminal , fall guy , follower , goat , goon , hatchet man , mercenary , myrmidon , page , participant , satrap , shill , thug