Eternal HERO

The Eternal Heroes are DARK counterparts of the used by  in the  anime.

Because they are DARK counterparts, their Attributes are obviously DARK. In addition, their names are always treated as their Elemental Hero counterparts (i.e. "Eternal Hero Avian's" name is always treated as ""). Thus, they can be affected by cards such as "", "", "", etc.

Their Fusion counterparts are, too, of the DARK Attribute, and their names are always treated as their "Elemental Hero" Fusion counterparts. They can only be Fusion Summoned through cards that can only Fusion Summon DARK Fusion Monsters (mainly "Darkness Fusion" and "Darkness Calling", in this case). The method in which they are Fusion Summoned is similar to how the are Summoned, mainly through Fusion Summon ("", in this case).