Dark Ranger

Dark rangers are undead archers in service of the Forsaken and led by Ranger Lord Nathanos Blightcaller. These cunning individuals, adept at manipulating opponents, are mainly composed of forcibly raised Farstrider rangers of Quel'Thalas. They now enjoy nothing more than sowing dissension and hatred within the enemy ranks. The Forsaken use dark rangers as elite agents or as the personal guards of the Banshee Queen, Sylvanas Windrunner. They had a great presence in Silverpine Forest and Hillsbrad Foothills.

Wrath of the Lich King
The dark rangers joined the Forsaken assault into Northrend, and many were seen as part of the Hand of Vengeance. After the liberation of the Undercity from the traitors Putress and Varimathras, the Forsaken as a whole came under scrutiny, and the Kor'kron Elite were stationed in the Undercity. Among the changes made were the additions of Dark Ranger Clea, Dark Ranger Cyndia and Dark Ranger Anya, now serving as the elite patrols within the Undercity, replacing the Seekers.

As the war in Northrend drew to a close, Lady Sylvanas herself traveled to the Frozen Halls to take vengeance upon Arthas. Dark Ranger Vorel enlisted agents of the Horde to meet with the Dark Lady along with Dark rangers Loralen and Kalira. Loralen is ultimately slain by the Lich King, though Kalira manages to gather reinforcements in the form of Orgrim's Hammer in order to escape the halls.

Their sudden reappearance during the War Against the Lich King would foreshadow the introduction of the hunter class to the Forsaken.

Cataclysm
Following the death of the Lich King, the Forsaken have reinforced their territories with their culture seen briefly in Northrend, and are taking on a far more aggressive stance in their war against the remnants of the Scarlet Crusade, the Scourge, and the Alliance. The Dark Rangers have taken on a more visible presence, and are seen throughout Silverpine Forest, Arathi Highlands and Hillsbrad Foothills.

A number of dark rangers accompany Lady Sylvanas in the Battle for Gilneas. They discover the Scythe of Elune, the likes of which would allow the Forsaken to have full dominion over the Worgen, though it escaped their grasp.

Under the command of Dark Ranger Alina and Galen Trollbane, the Forsaken have set their sights on the Arathi Highlands. Alina believes that the fallen nation of Stromgarde would make a fine setting for a new Undercity.

Dark rangers are seen with domesticated spiders during the Hillsbrad conflict, doing battle with the Bloodfang Worgen. They are empowered by Helcular.

With the Scarlet Crusade on its last legs, Dark Ranger Velonara is out to remove the last traces of it from the Forsaken territory. Velonara later traveled to the alternate Draenor.

Legion
Nathanos Blightcaller has recently been training a new generation of Forsaken rangers comprising of undead humans, making the undead racial composition of the order more diverse. These Forsaken hunters appear to favor the woodsman axe and the crossbow in contrast to the bow and arrow typically employed by their undead high elf counterparts.

A contingent of dark rangers led by Dark Ranger Velonara has also joined the Unseen Path.

Before the Storm
Sylvanas took 200 dark rangers to Thoradin's Wall as the Gathering occurred in the Arathi Highlands. When Sylvanas noticed the Forsaken of the Desolate Council walking towards Stromgarde Keep, defecting to the Alliance, she ordered the dark rangers to kill every Forsaken on the field but spare the humans. The rangers mounted bats and carried out the task, harming no humans. Then they regrouped with Sylvanas where she just killed Calia Menethil. As King Anduin Wrynn gathered Calia's body, Sylvanas and her dark rangers simply left.

Battle for Azeroth
Dark rangers participated in the War of the Thorns and other major conflicts of the Blood War.

Several night elf dark rangers were raised by the Horde, including Delaryn Summermoon as their new captain. Sira Moonwarden, also raised by the Forsaken, has the title "Dark Warden".

Appearance and attire
Dark rangers are most commonly undead elven women, with blood-red eyes and deathly pale skin. Typically, they are clad in a leather-looking outfit complete with a hood, which could be seen as a dark twist of the Farstrider attire. Nearly all of them are seen with a cloak. Dark Ranger Anya is a prominent example of this style.

Nathanos Blightcaller has recently been training a new generation of Forsaken rangers comprising of undead humans, making the undead racial composition of the order more diverse. These Forsaken hunters appear to favor the woodsman axe and the crossbow in contrast to the bow and arrow typically employed by their undead high elf counterparts. Like Nathanos, they sport a leather-looking outfit and optionally a hood and face mask.

Races
Nearly all dark rangers are undead high elves found only among the Forsaken. No other faction has the elves' history coupled with the personal knowledge of shadows to learn the arts of a dark ranger. In fact, many dark rangers refuse to teach their arts to anyone who wasn't a former elf. While these rangers have slackened their restrictions some, most dark rangers were once elves.

There has been only one recording of a human ranger and subsequent dark ranger. Nathanos Blightcaller's resurrection as one of the Forsaken and service to the Dark Lady has earned him the rank of Champion of the Banshee Queen. He used to reside at Marris Stead in the Eastern Plaguelands but now resides in the Undercity teaching hunters to learn new talents. Nathanos has recently been training a new generation of Forsaken rangers comprising of undead humans, making the undead racial composition more diverse.

During the War of the Thorns, lots of night elves were killed. Sylvanas and her Forsaken would later take that chance and raised them into their ranks turning some night elves into loyal dark rangers.

See WoWPedia