The word “villain” comes from the Latin “villanus” meaning “farm servant”.
In Medieval Europe many peasant farmers were “owned” by their masters and had to work for them for free. Being slaves, they were frequently sold from one person to another. When the word “villain” first entered the language, it did not have a negative connotation; it did not mean an evil person, as it does today. But since the original “villain” was poor, he often has to resort to little bit of stealing to survive.
The aristocratic landlords, however, began to associate all sorts of bad things with him. As a result, the word began to be associated with a person of low morals. As time went by, “villain” began to acquire the negative meaning that it has today. Do you know that the word “villain” and “villa” are related? In the old days, villains lived in a villa! When we think of a “villa” now, we think of something fancy, but the original meaning of “villa” was “farm”. Perhaps we should start calling farmhouses “villas”!