I am looking for a term meaning "a name used as an embodiment of a concept".
For example, Quisling, which originally referred to a specific person, has taken on the meaning of "traitor." A Mary Sue is a flawless self insert. A Casanova or Don Juan is an overabundant lover. In TV tropes speak, a Scrappy is a generally loathed character, but the term itself came from Scrappy Doo. (These are all my approximations of the definitions, obviously.)
Is there a name for this type of word? I don't think it's quite metonomy or synecdoche. However, I'm not sure.