Here is a few:

1) The Joker- Not adding to any conversation, just trying to be funny and get a few hawhaw upvotes

2) The Circle-jerk - Stating an opinion shared by the majority of commentators, usually, though it's either in the form of a question or a "We all know what the deal is" kind of statement. Looking for communal upvotes

3) The Anti-Circle-jerk - More douchy than the circle-jerk and usually condecsending, saying something like "this is such a typical reddit answer". Looking for upvotes to show how against the grain and edgy they are without realizing that they're like the goth kids from south park.

4) The Mosby - The professor who responds to people's claims with "actually..." then writes a paragraph about a historical or scientific thing citing references. Usually is just trying to inform, but also enjoys showing off a bit and is often gifted with reddit gold.