In Soulcalibur II, Nightmare's armor changes design, now sporting long red hair from the back with bat wing-like ornaments on the sides replacing the horn.

During the events of Soulcalibur, he was simply a suit of armor with a giant arm and horned helmet. Over the years, his appearance has progressively grown more and more demonic, as influenced by the state of Soul Edge himself. He is depicted with Soul Edge in his left hand, symbolizing his polarity with Siegfried. His prominent feature is his right arm, which has been twisted and transformed into a large three-digit claw whose flesh overlaps his entire right arm and shoulder. True to his nickname, Nightmare appears as a dark figure covered in dark blue armor that covers most of his body. The Nightmare appearing in Soulcalibur V, Soulcalibur: Lost Swords, and Soulcalibur: Unbreakable Soul is Soul Edge possessing the body of Raphael and plotting behind the scenes under the alias ' Graf Dumas' as he plans to resurrect the full power of Soul Edge. The Nightmare appearing in Soulcalibur III, Soulcalibur Legends, and Soulcalibur IV is Inferno possessing Siegfried's discarded armor. In the Soulcalibur: Spirit Sword manhua, Kilik and later Astaroth are possessed by Soul Edge after Siegfried and become Nightmare. The Nightmare seen in Soul Edge, Soulcalibur, Soulcalibur II, and Soulcalibur VI is Siegfried Schtauffen, possessed by the cursed sword at the end of Soul Edge. No matter the host Nightmare always has the same personality, though he only seems to form if the sword is wielded by a special man. Nightmare has been present in one form or another due to him being an animated armor, his possessing of bodies or the power of Soul Edge keeping him alive in most games after.

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