1-The Good Guys
For a long while, the inhabitants of a province were preyed upon by a drugs cartel. When the cartel started protection rackets, at first the people they preyed upon did not mind too much and reluctantly accepted paying tribute. The local police were either secret cartel members themselves or too scared to interfere. Over time, the cartel started demanding more and more money, forcibly addicting people to drugs, murdering popular people and even forcing themselves on women and girls. Finally, some of the people could take no more. Smuggling weapons in from a nearby country with lax weapon laws, they set upon the cartel members, killing fourteen in a single day. Within days, the cartel members had either been killed or fled for their lives, the cartel leader being captured alive and pubically strung up in the main square. Things may change in time, but for now most people in the region heartily approve of the vigilantes and see them as the Good Guys.
2-The Hired Henchmen
Plagued by repeated thefts of their horse and cattle herds, and rightly or wrongly blaming the small ranchers and local farmers for it, the rich cattlemen of the region have hired gunmen to defend their interests and herds. A number of their targets have already been shot down or strung up, but at a cost-the fearful and furious small rangers and farmers are on the verge of starting a counter-vigilante group of their own. If that happens, a lot of blood will be shed on both sides before one side or the other wins. The local sheriff and his deputies are trying to deal with the killings and bring people to justice, but lack enough evidence and are acutely aware that they are heavily outnumbered.
3-The Awful Lawfuls
When they first took up arms, it was to deal with a band of horrible murderers and rapists, and they were widely applauded by most people when they lynched or chased out the members of that band. Having dealt with them, they went after arsonists, robbers and burglars too and dealt with them. Within only a year they had put an end to all serious crime in the area. Unfortunately they had so much fun doing it that they didn't know when to stop. Had they disbanded then they would have been seen as heroes throughout the region, but instead they went after petty thieves and beggars, then arguing couples and those they thought were lazy, and then anyone they disliked, including local law enforcement ,whipping them or outright lynching them. Again, people are on the verge of forming a counter-vigilante group to deal with them.
4-The Masterful Mafiosi
These vigilantes have impersonated bad elements and then ridden in to *deal* with them, with some impressively choreographed fight scenes that seem real. Having driven the *bad guys* away, they accepted a reward from the townspeople and since then have been running a de facto protection racket, with the difference that so far at least, the townspeople don't know that the *bad guys* who trouble their town and the *good guys* that they pay to keep the *bad guys* away are in fact in cahoots with each other and part of the same large gang. Whenever the town elects a sheriff and deputies, the *bad* part of the gang swiftly murders them, so that only the *vigilantes* can keep criminals out of town.
5-The Sneaky Squad
In this case the vigilante group secretly operates within the ranks of the police itself. Fed up with the high crime rate of the area, they have started planting false evidence on people, killing them and planting weapons in their hands, or dumping known gang members in the territory of other gangs to be murdered by the other gangs. The brass has it's suspicions but apparently not enough evidence yet to act. Perhaps some of the brass secretly think the Squad is doing the right thing.
6-The Vallient Vampires
For a modest *rent* paid in willingly given blood, these vampires protect the poor and the outcasts of society from the criminals that prey on them. After a few of the nastier criminals were found dead and drained of blood, the rest know to give the area a wide berth. The vampires are widely popular, even more so given that the City Guard rarely bother to investigate crimes against the poor, and the vampires get all the blood they would ever need and genuinely protect the community.
7-The Worried Warriors
"Are you really sure we need to kill them? Can't we just give them a warning?"
"I hate breaking people's legs, it makes me feel sick."
Unlike the other vigilante gangs in this submission, this gang of reluctant vigilantes hate what they are doing and would much rather not do it at all, but they feel that because the local law enforcement is unable or unwilling to deal with the crime in their area, they have no choice but to hand out some violent DIY justice. They would much rather just leave someone bound and gagged as a warning then beat the person, and they would much rather beat a person up then murder them. But they have forced themselves to leave people hanging by their necks from trees in an event to lower the amount of crime in their area as a last resort. They look forward to when they think the time is right to disband.