Trolls (preferably always plural) are users who annoy other users sometimes. In other words, all users. It is technically correct to refer to anyone who has no sysop power as a troll: the terms are mutually exclusive to most users.
Please note that this is not true of vandals, as there is sysop vandalism, a form of official vandalism in which those who have preferential power to delete or hide comments or pages use this to advance their POV.
It is also true that people who have no sysop power have sometimes chosen to have no sysop power. In democratic domains which elect sysops or more anarchic troll-friendly ones where all users are sysops, objections to sysop power should be much more muted.
From new troll point of view, sysops are called old trolls: they arrived first but did not necessarily have any particular insight or skills or judgement that should require them to remain in charge. The use of term:old specifically for the faction in power seems to imply that they will inevitably lose power to newcomers, new trolls.
 All users are trolls
An alternate explanation is that all users are trolls. Note: if you wish to make this claim, please link to [[all users are trolls]] not [[trolls]]. If you assume that all users are not trolls, it's sensible to ask "who is":
There are as many types of trolls as there are reasons to use the net, please see en: wikipedia: Internet troll (a sysop-biased view).
A troll-friendly wiki is one wherein sysops never use technological or ownership powers to limit debate. Most wiki best practices rely on holding off using these, and letting situations between trolls resolve socially. On very large public wikis it is common for factions to form, but this may not be required on those with under 150 users. Appointing a Lowest Troll to appoint mediators and arbitrators trusted by both sides, and to engage in counter-trolling (usually taking the form of friendly rhetoric and satire, but potentially savage personal criticism if this seems to be absolutely required to get someone to stop carping about others and start taking a good look at themselves).
In wiki troll culture, trolls are generally benign since there are fewer artificial scarcities (plenty of namespace, for example), but they can bite you on the leg if you do things against their bodily interest, or that of their family and friends, or against the environment. A troll-sysop struggle may end up in:
- people being driven off by trolls
- cries that trolls have taken over
- outbreaks of sysop vandalism as sysops try to make the wiki useless to trolls
Some view all of these as normal, others consider them terrible, awful and preventable by pre-emptive authority. Those who believe this last tend to be perceived as political centrists. By contrast, Greens are generally friendly to trolls as they are an endangered, planet-protecting species, but also because Greens are used to being bit on the leg by the things they protect.