Ghadius (ガディウス, Gadiusu) is a villain who played a major role in Klonoa: Door to Phantomile and its Wii remake.

Ghadius the Dark King is the main antagonist of Door to Phantomile, who wants to obtain the Moon Pendant to open the door to Cress, the Moon Kingdom. Once in the Moon Kingdom, he awakens the Perfect Nightmare, Nahatomb, to destroy the world. Most of the leg-work is done by his sidekick, Joka.

For the most part, Ghadius acts as your traditional pantomime villain. When first revealed, his motives do not appear to extend beyond simple revenge and destruction. He displays little emotion, and bursts into foreboding laughter with unpredictable frequency. He has a contemptuous nature towards the people of Phantomile - with the exception of Joka, whom he shows some fondness of. This contempt is revealed to stem from the Phantomilians reliance on light and 'good dreams'. Ghadius, as a King of Darkness and Nightmares, was shunned and forgotten by the people of Phantomile. This led to his belief that, if the world would abandon him, then he, in turn, may abandon the world.

He refers to Klonoa as a 'strange dream'. Aside from Huepow, he is the only character in the game who displays some knowledge of Klonoa's true identity.

Ghadius demonstrates views of both nihilism and narcissism. He disregards and is willing to destroy all of Phantomile simply because he is not allowed to be part of it. He considers his feelings and emotions to be above that of the Phantomilian denizens.