"Robin Shoots with Sir Guy" by Louis Rhead. Illustration to Bold Robin Hood and His Outlaw Band: Their Famous Exploits in Sherwood Forest: Guy of Gisbourne acts as the Sheriff of Nottingham's henchman
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.
The first part of the word, which is recorded in English since 1360, comes from the Old Englishhengest, meaning "horse", notably stallion, cognates of which also occur in many Germanic languages, such as Old Frisian, German and Dutchhengst. The word appears in the name of Hengest, the Saxon chieftain, and still survives in English in placenames and other names beginning with Hingst- or Hinx-. It was often rendered as Henxman in medieval English.
Young henchmen, in fact pages of honour or squires, rode or walked at the side of their master in processions and the like, and appear in the English royal household from the 14th century until Tudor Queen Elizabeth I abolished the royal henchmen, known also as the children of honour.
The word became obsolete for grooms in English from the middle of the 17th century, but was retained in Scots as "personal attendant of a Highland chief". It was revived in English by way of the novelist Sir Walter Scott, who took the word and its derivation, according to the New English Dictionary, from Edward Burt's Letters from a Gentleman in the North of Scotland, together with its erroneous derivation from haunch. The word is, in this sense, synonymous with gillie, the faithful personal follower of a Highland chieftain, the man who stands at his master's haunch, ready for any emergency.
The modern sense of "obedient or unscrupulous follower" is first recorded 1839, probably based on a misunderstanding of the word as used by Scott, and is often used to describe an out-and-out adherent or partisan, ready to do anything.
Henchmen (occasionally henchlings) are common in mystery, fantasy, adventure comic books, and adventure novels and movies. They are the expendable adherents of the main villain, always there to do the master's bidding, to kill or be killed, kidnap, or threaten, as needed. Often, they are killed by the hero before the master villain is reached, by the hero's sidekick in a dramatic battle, or even by the master villain as punishment for failure to comply with orders. They also may switch sides during the course of the story to ally with the hero. Alternatively, they may be forgotten in the heat of the climax when the master villain is defeated, then killed when they reappear in the denouement for one last scare or even promoted to master villain for a sequel.
Henchmen are often abused and insulted by the villain for their incompetence, or for his pleasure; indeed, some abused henchmen take revenge after the villain's final defeat at the hero's hands, so that the henchman rather than the hero actually kills the villain. Henchmen in this sense are also sometimes called lackeys, toadies, or mooks (with the latter term more often used for lesser minions of the villain).
Not all henchmen are dimwitted, expendable employees of a villain. Sometimes, they may be of an equal social standing or at least have a high intelligence or social standing of their own, thus being valued more like a right-hand man. In such cases, they may command groups of more expendable thugs. This is common in ensemble casts where often the leading villain remains behind the scenes. Being granted a large amount of autonomy, intelligent henchmen often have their own agendas and may also covet the leading villain's position, and they often attempt to betray the villain in order to obtain it. Some henchmen even serve the hero, such as in Star Trek.
While the term is masculine, female henchmen are not unheard of. However, many of them typically serve only as the male villain's lover, rather than actively take part in the schemes. Usually, there is, instead, an additional male accomplice for the purpose of criminal business. A female accomplice is more often called a "moll."
In fiction, such heroic supporting characters are normally portrayed in a more positive light, tied to the hero by bonds of friendship and loyalty and are usually called sidekicks; the villain's supporters are called henchmen or minions because of their evil nature, which implies that such personal bonds are difficult to establish. However, some darkly comedic heroes have sidekicks of a more subservient nature; though these relationships are often a form of "tough love" or even just a condescending affection, the henchman is in this case usually known as a minion.