Cazarim

Cazarim's Background
Though the exact origins of the Nathrezim remain a mystery, one thing is for certain - Cazarim was sent to Azeroth under the command of Kil'jaeden himself prior to the beginning of their third invasion, wanting the Dreadlord to bring chaos to the innocent planet and it's inhabitants for the Legion's coming. To achieve this, Cazarim ventured across Alliance territory, spreading rumours of the end in disguise and marking down target civilizations that need to be taken down. To name a few, Cazarim proposed to strike down Thelsamar in Loch Modan to provide the Legion an even stronger foothold against Ironforge, Darkshire in Duskwood due to their weak defenses and close proximity to Karazhan, a beacon of power Kil'jaeden would keep his eyes on and Sentinel Hill to grant the Demonic Crusade a fortress near Stormwind. During his mischevious work within the Eastern Kingdoms, a Shadow approached him, the Dark Mage... He wished to side with the Nathrezim, promising his even more vantage-points to exploit. Together they took Stonewatch Keep in Redridge and begun to corrupt the local Dragonkin from the inside, aggravating them to one day strike Stormwind from the sky.

Defeat
Though he was sure of his success, two Worgen who sought to stop the Dark Mage's work in Stonewatch evitentally cast Cazarim back into the Twisting Nether with the help of Venorion the reanimated. His fang was taken by Fenrissa as a relic of power to draw life from enemies upon striking a powerful blow.

Like is with any Demon or Dreadlord, it is only a matter of time till Cazarim returns... and when he does. Who knows what burning rage he has towards those who defeated him.