Often found roaming close to altars dedicated to Daedra worship, the Vigilants of Stendarr are tbe warrior monks of Skyrim who spend their lives in service to Stendarr, the God of Mercy, eradicating evil wherever they come across it. Through the events of the Dawnguard DLC, they are all but eradicated in a single night by the Volkihar vampires, which sparks the events of the story.
As a relatively new order compared to many others in The Elder Scrolls, there isn't a great deal of history surrounding the Vigilants, with many aspects of their group only being told through dialogue or implied connections.
10 Founded Because Of The Oblivion Crisis
Following the Oblivion Crisis and the events of The Elder Scrolls IV: Oblivion, the Vigilants of Stendarr were formed in an effort to make sure that the Daedra never threatened Tamriel in the same way ever again. It's never specified why the Vigilants are worshippers of Stendarr specifically, but they are clearly devoted to their Divine of choice, with each member wearing an Amulet of Stendarr as well as a Shrine to Stendarr appearing in the Hall of the Vigilants.
9 They Don't Just Hunt Daedra
Although their main focus is on the eradication of the Daedra from Tamriel, the Vigilants don't limit themselves to just the denizens of Oblivion. Since Daedra appearing in Tamriel is quite a rare occurrence when not summoned, they spend more time hunting anything that threatens the lives of mortals, including werewolves, vampires, and witches. However, this could also be because of their ties to certain Daedric Princes, with werewolves being tied to Hircine, vampires to Molag Bal, and witches generally worshipping any one of the Daedric Princes.
8 They Search For Daedric Artifacts
Not simply satisfied with eradicating all Daedra, the Vigilants also want to remove their influence from the world as well. This means tracking down every Daedric Artifact they can get their hands on and destroying it, though they have yet to find a single one.
If the player interacts with a Vigilant while wielding a Daedric Artifact, such as the Mace of Molag Bal or the Ebony Blade, they will quickly become hostile and try to take the item from you. The same effect can be created by equipping Daedric armor as well, though they won't talk to the player beforehand.
7 Their Ironic Choice Of Divine
Stendarr, in the eyes of the Imperial pantheon, is said to represent righteous rule, forgiveness, and mercy, though this differs wildly depending on which iteration of them is being worshipped. Considering they are named the Vigilants of Stendarr, it would have been accurate to assume that the Vigialnts themselves were a merciful group, but that couldn't be further from the truth. As they say in some dialogue "May Stendarr have mercy on you, for the Vigil has none to spare", indicates that they may not stick as strictly to the ideals of their God as they would have people believe.
6 They're Not Very Good At Their Job
At first glance, it would seem as though the Vigilants are a group of decent warriors who hunt down evil wherever they find it, but they are a lot worse at their job than they would otherwise seem. They set up the Hall of the Vigilants, their main base of operations, a stone's throw away from Dimhollow Crypt, with only one Vigilant believing it was of any significance. Unfortunately for the Vigiants, they failed to realize that it held huge significance for the Volkihar vampires, as well as housing one of the oldest vampires in existence, Serana, inside it.
5 They're Not Associated With The Dawnguard
Considering Isran's obsession with vampires and his desire to bring the Dawnguard back to its past glory, it would be assumed that the Dawnguard and the Vigilants were associated with one another at one point in time. However, they were created and dissolved so far apart from one another that it's any wonder Isran found out about them in the first place. The Dawnguard was created some time in the Second Era, around 1000 years before the Vigilants were formed following the Oblivion Crisis and the initiation of the Fourth Era.
4 Stendarr's Nordic Equivalent
As each race in Tamriel has a different interpretation of the creation myth, they also each have a different way of viewing the Divines and Daedric Princes. Stendarr's equivalent to the Nords is Stuhn, the brother of Tsun and a warrior god who fought against the Aldmeri pantheon of gods. According to their religion, Stuhn taught man the benefits of war, including taking prisoners.
This version of Stendarr is very different from the Imperial interpretation of him, which most likely stems from the Nordic's love of battle and conquest compared to the Imperial's stance on royalty and rule.
3 Keeper Carcette Might Not Be Dead
After the player enters Fort Dawnguard, they can listen in on a conversation between Isran and Vigilant Tolan where he tells Isran that the Hall of the Vigilants has been destroyed, with the majority of the Vigilants now dead. He also mentions that Keeper Carcette, the head of the Skryim branch, was one of those killed in the vampire attack. However, if players go to the now destroyed Hall of the Vigilants, Keeper Carcette's body is nowhere to be found, indicating that she might not be as dead as Tolan thinks she is.
2 Brother Adalvald Can't Count
Towards the end of Dimhollow Crypt, the player can walk in on two vampires interrogating a Vigilant known as Brother Adalvald, who had a strong feeling that the dungeon held significant importance to vampires. Near his body is a book titled Notes on Dimhollow Crypt, Vol 3, but there is a slight problem with his ability to count since there isn't a volume 1 or 2 at all in the game. It could simply have been removed from the game, but considering how laser-focused he was on Dimhollow Crypt, he may have forgotten to write parts 1 and 2 altogether.
1 They're Most Likely Going To Be Wiped Out
The Vigilants lasted a good few hundred years before the events of Dawnguard, but it's likely they won't survive much longer in the Elder Scrolls timeline, particularly in Skyrim. The few remaining Vigilants wander Skyrim in the vain attempt to keep up the good work, but considering how few there are left and the fact that Isran, their only potential ally, refuses to help them, they likely won't last into The Elder Scrolls VI.