No-Life King

The No-Life King (不死の王, Nō-Raifu Kingu; lit. Undying King) is a mysterious and powerful figure who once ruled Grimgar over a century ago. After his supposed defeat, his curse of the Undead still lingers in Grimgar.

Soma's clan, the Day Breakers, have announced that there are indications in the lands of the Kingdom of Ishmael of the King's return.

The real name of the No-Life King appears to be Enad George, as stated by Jessie Smith, who apparently knows a lot about the history of Grimgar. Enad George is referred to as the founding King of Arabakia.

History
While his lore is still unclear.

Undead
According to Honen, Undeads are the result of any corpse that is not properly cremated within three days. Dark spells are less effective on them, they are resistant to physical damage, and will continue to fight until they are hit by Dispel.