History
D`grth is one of the hundred gods of a land of swords and sorcery (where Stalker is from). He is, naturally, a god of darkness, and he has his own Hell which he rules.
He became Stalkers enemy, when Stalker traded his soul in exchange of being a great warrior. D`grth didn`t tell him though, that Stalker wouldn`t have any more feelings, once he didn`t have his soul anymore. This made Stalker vengeful towards the evil god.
When Stalker journeyed to D`grths domain, the evil god sent his forces to eradicate Stalker. They failed at this. When Stalker finally got to D`grth, he demanded his soul back. D`grth told Stalker that it can`t be done. Because, now that D`grth has Stalkers soul, it`s a part of him, and it will be until he dies. And a god can only die (completely) when nobody believes in that god.
Stalker vowed to kill everyone who believes in D`grth. The series ended at that, because DC was cancelling various poor selling series at the time.
Apparently though, D`grth hadn`t died, because he later appears in a story arc in Wonder woman, as also does Stalker.
Creation.
D`grth was created by Paul Levitz and Steve Ditko.