How about the 'Say & Walk Aways' the ones that seemingly try to spark a conversation either by OP or comment and are never heard from again when someone took the time responding to them.

Another one is the 'Drag it out of Me' type that somewhat resembles the Reassurance Junkie & Attention Whore. They will start a incomplete story raising more questions than answers and wait for good-willing people to help them clear up what is meant.

Finally the 'Off Topic/Comment Commentators' the ones that hijack discussions and (top) comment sections with the (intentional?) goal of diverting from the topic discussed. This could be dangerous spamming shills as well.