The Cyberdemon is a demon of immense power and furiosity and will be the main antagonist of the upcoming crossover, Kingdom Hearts: DOOM and is the first boss encountered in DOOM.
Prior to Kingdom Hearts: DOOM/DOOM Edit
The Cyberdemon's origins came about as the result of the discovery of remains of a creature known as a Baalgar Demon during an expedition into the demon's home realm during the UAC's Lazarus project. While intially it's intended reconstruction was for an exhibit, reconstruction was eventually retooled to create a weapon using High tech weaponry and an Argent accumulator. At an unknown time, the demon was given a neural pathway to allow itself to transfer Argent energy to parts of it's body where it was needed. This in turn, caused it to immediately restore it's own motor function and started causing havoc until it was once again contained at the cost of one of the researchers.
Kingdom Hearts: DOOM Edit
To be added.
At an unknown time following the release of the Demons on the UAC Argent facility and the death or possession of almost all it's personel, the Cyberdemon was released from it's containment either through managing to restore it's own motor function or suggestion from a higher form of being. Shortly after being free, it later encountered the Doom Marine whom was at the time, attempting to return to demon's dimension in an effort to end the invasion. While the marine was initially successful in reaching the realm by using the Cyberdemon's own accumulator, it was also transported where it was revived though eventually fatally defeated by the marine.
The Cyberdemon is seen as a large towering demon (it's size possibly equaling to that of a Darkside Heartless if not, slightly smaller or bigger). The demon also has cybernetic components as a result of the UAC's Lazarus project implanted on to it's body with the most obvious being it's right lower leg, the large rocket launcher in the place of it's left arm, and an argent accumulator in its' chest which allows the Cyberdemon to transfer argent energy to various parts of its' body. The demon also has a large claw on it's right hand, for it which it can use to release a wave a hell energy at it's target and later create to massive walls to create a corridor to close the space between the Cyberdemon and it's prey.