Kylmyys is the home planet of the Necrofriggians, Psycholeopterrans, and the Thermoscorians in the Ben 10 Universe.


Based on fossil records and recovered ancient tech, hundreds of thousands of years ago, Kylmyss was home to a species known as the Eter'Caneic, an industrial people that sought out the stars and desired to achieve interplanetary travel. Rather than building ships to travel off world, they attempted to make the entire planet mobile by making devices known as World Pilots, artificial active volcanoes that tapped into the molten core of the planet, and would be used as rockets and propel the planet across the universe.

Upon activation, the combined temperature of each World Pilot overheated the atmosphere and burned up all the oxygen, killing most surface life in minutes. With the engines left unsupervised, a mass meltdown occurred, drowning the surface in molten metals, as well as evaporating its oceans. It is theorized that over a thousand or so years, the extreme temperature increase worked its way through the planet, melting it down into a molten metal mass, and shortly after, triggered an Ice Age level temperature shift in an attempt to repair itself. Through this, the ocean's vapor re-condensed, cooling the planet's surface to a solid metal, and freezing the outermost layers of the ocean into ice caps that still stand today.


Kylmyss appears to be a barren frozen wasteland, but the planet's core is composed primarily of sulfurous magma, the heat of which creates vast oceanic pockets below the ice caps of the surface.


Two of the main landmarks include the Friggian Caps, the home of the Necrofriggians, and the Doused Divide, a large open oceanic ring surrounding the planet's core, which sits between two very different temperatures, making for a cold, yet balanced ecosystem teaming with life all the way down to it's metallic floor, which is the home of the Thermoscorians.



  • Scutum, the district that this planet exists in, is 174 light years from Earth.
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