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- This monster is the cover card of Structure Deck R: Advent of the True Monarch and its TCG counterpart, Emperor of Darkness Structure Deck.
- Erebus, in Greek mythology, is the personification of Darkness, and the brother-mate of Nyx , the personification of the Night.
- This monster appears in the artworks of "The First Monarch" and "Domain of the True Monarchs" as a silhouette. It also appears clearly in the artworks of "Pantheism of the Monarchs" and "Reawakening of the Emperor".
- It is interesting to note that the card "The First Monarch" can be Special Summoned as a Fiend-Type/Level 6/ATK 1000/DEF 2400 monster, while "Erebus" is a Zombie-Type/Level 8/ATK 2800/DEF 1000 monster.
- The aforementioned artworks also suggest that he was the First Monarch, implying that he had died and was later resurrected as a zombie-type. Another explanation could be that, if following the Greek mythological background. Erebus was one of the first beings to come into existence (as one of Khaos's children), which would literally make Erebus the first of the Monarchs to have existed.
- The artwork of "Pantheism of the Monarchs" seems to imply a possible connection between Erebus and "Ehther the Heavenly Monarch".
- In Greek Mythology, Aether (the deity Ehther appears to be inspired from) is the child of the god Erebus.