I'd say "autocrat" too, in most all scenarios. I suspect some people do both, on occasion.
Are we talking about online, or real life?
I'd generally say anonymous for both. How many people stir the pot by posting as anonymous, and how many in real life, especially in the media stir the post by saying something that they claim is true but their source is anonymous? To me, anonymous is synonymous with non-credible.
People who post anonymously are soon found out, and they do it to stir the pot because they don't have the guts to confront people with what they want to say.
Well you cannot hide behind an autocrat they will make you bow before them so i guess anonymous. Unless you are talking about the merging tool, guess I just dated myself.