A Troll in Internet Slang, is someone who intentionally says or does stuff to upset people or provoke a reaction.
In Mike's streams (and among the community in general) trolls more-or-less refer to very strange or semi-malicious users with gimmicks. Usually the more interesting trolls will actually earn a place on this wiki.
While it's unknown whether these types of trolls showed up before or after the Albert incident, you can be sure that they got a bit more "trendy" after it. Some time after Albert got banned, there have been an increase in joke accounts, posting walls of text, making insulting remarks, saying things that are out-of-line with the rest of the chat. Also they sometimes have really really ridiculous usernames.
A few of the earliest examples that can be traced back to would be Gorillz, Mr. Jizz, and Kurt Angle. These three had weird gimmicks which caught on to a few users in the chat. Later examples would be the likes of Kez, and Zuzzy.
These trolls earn a place on this wiki for actually being memorable.
However, the more malicious kinds who lack a gimmick (IE their only gimmick is malice or bigotry) and no entertainment value don't earn a spot or even deserve to be remembered.
Of course now there are some new ones actually trying to get a page on this wiki by forcing gimmicks and I'm just going to say "No, it doesn't happen that way." But then again what do I know I can't stay consistent on anything lol.