Declan Akaba with "D/D/D Wave King Caesar", "D/D/D Flame King Genghis" and "D/D/D Gust King Alexander".
"D/D/D" stands for Different Dimension Daemon. Taste the power of demon kings that have conquered different dimensions.— Declan Akaba on the D/D/D.
So far, most "D/D/D" monsters have been named after either a historical person, usually a military leader, or some form of the end of the world (e.g. "Armageddon") and they encompass all of the Extra Deck Summon Monsters as well as some Main Deck Effect Monsters. Most of them have an attributed office role from a pun on their name, creating Demonic hierarchy themed archetype.
The "Superdoom King" monsters are all based on past main antagonists from previous series.
- Purplish Armageddon: Zorc Necrophades and Nightshroud.
- Whitest Armageddon: Z-one
- Darkness Armageddon: Don Thousand and the Barian Emblem that serves as his symbol. It also has the same name as Nightshroud's Japanese name, Darkness.
According to Declan Akaba, "D/D/D" is short for "Different Dimension Demon" (ディファレント・ディメンション・デーモン Difarento Dimenshon Dēmon).  This refers to how the "D/D/D" monsters consists of monsters of all Extra Deck Summoning methods, with each Extra Deck Summoning method (Fusion, Synchro and Xyz) originating from a different dimension in the anime.
The "D/D/D" archetype marks the first time that monsters with the word "Demon" (or "Daemon") in their names are released in the TCG, with said word intact. However since the word "Demon" is simply represented in the card names via an acronym, the use of this word is comparatively subtle, and the English anime does not have Declan mention this detail.