Venger is an evil wizard who wants to impose his tyrannical rule on the whole of the Realm.
Venger is distinguished by his pale skin, fangs and barbed bat-like wings, but more iconically by a singular horn on the left side of his head. It is unknown whether Venger ever had two horns and lost the right one, although there is a two-horned statue dressed similar to Venger in one of his castles but this is viewed from the back so the identity is hidden. Possibly it could be a statue of Venger from when he had two horns.
Venger's conquest of the Realm is prevented by Tiamat the dragon as he cannot defeat her and needs the six magical totems that the Dungeon Master gave the heroes which would increase his sorcery to a level where he could finally rival his dragon nemesis. He has confronted Tiamat once with the totems and used their combined magic to fire mystic bolts at her but as the totems were depleted he failed to defeat the dragon.
Venger's other nemesis is the Dungeon Master who gave the six totems he needs to defeat Tiamat the dragon to the heroes and then helps them to foil Venger's schemes with his cryptic advice. Other than the Dungeon Master's constant interference their rivalry has another aspect because the Dungeon Master is revealed to be Venger's father. This is implied at the end of the Dragon's Graveyard episode when the Dungeon Master refers to Venger as his son but confirmed in the Requiem script where he thanks the heroes for restoring his son to him by redeeming Venger of all evil influence with Venger addressing the Dungeon Master as his father. Whether the Dungeon Master is Venger's biological or adoptive father is not confirmed, and even Presto jokingly comments that there's not a big family resemblance.
Venger was originally a noble human but millennia ago made a pact with the Nameless One and chose to be mentored by the evil entity. This tutorship in sorcery would cost him both his humanity and human form, with the essence of his former self being locked inside a cenotaph located at the edge of the Realm. If the key to that vault is ever used to unlock it then Venger would be redeemed of evil and transformed back into his human and humane self. At the end of the Treasure Of Tardos episode Dungeon Master hints at this history by mentioning that there was good in Venger once but a long time ago, adding that everyone makes mistakes and that Venger was his.
Venger's body has been destroyed six times but he has somehow managed to resurrect himself. In all but one of these destructions his phantom self can be seen fleeing the place of his demise.
Dungeon Master describes Venger as a force of evil and warns the heroes about Venger's many faces of evil as he is prone to disguising himself as other people, although he has only practised such deception four times in the series to imitate Merlin, Hector the halfling, a prisoner in his own castle and a flying warrior.
Venger has a weakness in the form of the heart stones; crimson gems that by his own admission are the one element in the Realm that he is powerless against. He cowers from one such gem and has to get shadow demon to dispose of it, but when confronted with many he shatters into similar crimson shards and flees in a cloud of these gem fragments to resurrect elsewhere.
Venger appears in twenty of the twenty-seven episodes.