Nightmare

The Nightmare is the collective name for a number of artificial species created through genetic mutation and cybernetic enhancements, designed to be used as biological weapons. Information from UT2003 suggests that the Nightmare come from a lava planet called Purgatory or Abaddon, home to some of the game's maps.

All species seem to be based on Humans. A Nightmare team called the Black Legion is sent to fight in the Liandri Grand Tournament during the time periods of UC/UT2003, and UT2004.

The Nightmare consist of several species:
 * Homo Sapien Taratis - hybrid of Human and Taratic DNA.
 * Homo Sapiens Medusae
 * Cybernetic Humans - enhanced through the use of cybernetics

Necris
Some say the Nightmare are the Liandri Mining Corporation's failed attempt at reproducing the Necris process, but although the Liandri were involved in such experiments, it is unknown if the Nightmare are actually a result of these experiments.

The Liandri did pay the Phayder Corporation insane amounts of money to bring back the public's favorite Tournament contestants as actual Necris.