Black Widows is a type of Misandrist, this is a common type of villain in folklore, fictional works and real life. They are females who make a habit of marrying males and then murdering them in cold blood, most of the time for monetary gain, but Black Widows can also be a specific type of serial killer. They are an obvious subtype of femme fatales but are almost always deadly; that is unless they're caught in time.

Note: While some Black Widows are Misandrists, not all Black Widows are necessarily have to be a misandrist but it's possible for them to become misandrists, though murdering husbands can be what a misandrist does.