Archmage of the Kirin Tor
A legendary wizard, Khadgar is a master of the arcane arts and a constant thorn in the side of the Burning Legion.
Once the apprentice of the Guardian Medivh, Archmage Khadgar is a savvy veteran of the First and Second Wars. When he uncovered Medivh's scheme to open a portal from Draenor and unleash demon-tainted orcs on Azeroth, Khadgar confronted and helped defeat his master. During the battle, Khadgar was struck by a terrible spell that aged him dramatically. His body turned frail, but his mind remained sharp. After the orcs were driven back through the Dark Portal, Khadgar supervised the construction of Nethergarde Keep, a fortress built to watch over the breach between realms.
All seemed quiet at the Dark Portal, until the orc traitor Garrosh Hellscream carved a path into an alternate version of Draenor's past. There, he aided the legendary warlord Grommash Hellscream with forging an unstoppable army of orcs: the Iron Horde. Khadgar volunteered for the suicide mission into Draenor to repel the invaders—an effort that barely succeeded.
The armies of Azeroth then established a foothold on Draenor, and Khadgar turned his attention to what he saw as the true threat: Gul'dan. The warlock, a pawn of the Burning Legion, was running free in the shadows. The archmage worked closely with Azeroth's greatest champions to find and thwart Gul'dan, but in the moment of victory, the orc escaped to Azeroth.
Now Khadgar is determined to rally Azeroth's combined strength against the Burning Legion's invasion... and end Gul'dan's treachery once and for all.
Sacrifice. To the young it means to change, but to the wizened it heralds an end. I know both meanings better than anyone else.