Kierrok was created by Chthon the Elder God and was the master of the N'Garai who once ruled Earth millennia ago.
Major Story Arc
Night of the Demon
For more information see: The X-Men #96 - Night of the Demon!
Kierrok was accidentally released from his own dimension by Cyclops, who was lashing out with his eye beams, angry and saddened by John Proudstar's death. Cyclops' beams hit a magic obelisk called a Cairn, and Kierrok appeared and attacked the X-Mansion. Charles Xavier was overwhelmed by Kierrok's evil. Storm was able to find the obelisk and destroyed it, sealing Kierrok back in his own dimension.
Lair Of The N'Garai
For more information see: Wolverine Annual
An obelisk rose again and a demon escaped. It was found by a feral Wolverine who killed it. Wolverine followed another demon back to Kierrok's dimension and began fighting the N'Garai. He slaughtered many of the demons and was fighting Kierrok himself when Nightcrawler found them. Fearing that Wolverine could kill him, Kierrok banished them both back to Earth and sealed the Cairn.
Pixies and Demons
For more information see: X-Men Pixies and Demons
Kierrok and the N'Garai try to take over the world but are stopped by The X-men led by Pixie. who destroys their Cairn.