What is Henchman?

Legal Definition
Henchman referred originally to one who attended a horse for his employer, that is, a horse groom. Hence, like constable and marshal, also originally stable staff, henchman became the title of a subordinate official in a royal court or noble household. It is now used to generally describe any person with subordinate status derisively, while most often used specifically to a hired guard or minion of a villain or master criminal.
-- Wikipedia
Legal Definition
A page; an attendant; a herald. See Barnes v. State, 88 Md. 347, 41 Atl. 781.
-- Black's Law Dictionary