Skjor

 is a member of The Companions and one of the leaders of The Circle. It is assumed that Skjor is one of the highest ranked members of The Circle, quite possibly next to Kodlak Whitemane, as mentioned offhandly by Aela the Huntress and several other companions.

Background
Before becoming a Companion, he was trained as a Blade and fought in the Great War against the Thalmor before becoming critically injured in the fighting. Sometime before the Dragon Crisis, Skjor and Kodlak Whitemane supposedly led a charge against an Aldmeri forces of 40,000 mer all on their own -- though both played it off as a much smaller force.

Proving Honor
During the Dragonborn's induction into the Companions, Skjor sends the Dragonborn to Dustman's Cairn with Farkas to recover a fragment of Wuuthrad.

The Silver Hand
The Dragonborn learns Skjor and several other members of the Companions are werewolves and have constructed a secret faction known as The Circle. Shortly after, Skjor helps the Dragonborn become a werewolf as well. He is killed by Krev the Skinner, a member of the Silver Hand.

Quests

 * Proving Honor
 * The Silver Hand

Trivia

 * Skjør is Norwegian for fragile.

Bugs

 * Skjor may still be found alive after being killed in the quest "The Silver Hand." He will continue to state that the Dragonborn still needs to prove his or herself, even after reaching the noble rank of Harbinger. He will wander around Jorrvaskr and act just like he did whilst he was alive. This may or may not be due to Skjor being part of a different faction, causing him re-spawn when his character should die during the quest. Certain important characters re-spawn after being dead for one game month. In addition, he can also be found during a random encounter in the wilderness with a few other companions. He has been found both fully functional, and sometimes stuck in the ground, making no actions, but he can be interacted with. It is likely that after this encounter, he can be found once again in Jorvasskr, and will be able to give quests regarding "Speak to the Companions Leaders for work".
 * Solution: Open the console and type  after clicking Skjor.
 * Sometime after finishing the quest "The Silver Hand" Skjor may be found walking around in an area. He retains all of his equipment, moves around, but has no animations. Skjor cannot be interacted with, but he can be killed.

Скьор Skjor