User blog comment:LuluTDFan/What makes a good villain?/@comment-1874924-20131010221419

One important distinction to keep in mind is that "antagonist" and "villain" are two different things. A villain does things that the reader is expected to consider "bad", or at least morally ambiguous. An antagonist simply opposes the protagonist, usually because the antagonist's goals are in some way incompatible with the protagonist's (e.g. both want to win in a situation where there can be only one winner). There's naturally a great deal of overlap, but it's entirely possible to be one without being the other. While villain protagonists aren't terribly common (TDWT Heather is an example, if you accept that she's a villain at all), nonvillainous antagonists aren't all that rare. In the context of a competition story, a "strategybot" player (when not the protagonist) is a good example of an antagonist who may or may not also be a villain.