Dr. Psyche

Dr. Psyche is the "Computational Humanoid Reploid" from Mega Man X: Command Mission. His final form is the Mad Nautilus. Dr. Psyche is a member of the Rebellion Forces and is very interested in the evolutionary capabilities of Reploids. He was an old research partner of Professor Gaudile and urged him to join the Rebellion Forces as well. Dr. Psyche eventually hunted down his old colleague to wrest the Force Metal Generator device he had created and was confronted by Mega Man X in doing so.

Upon his defeat at X's hands, Dr. Psyche separates his head from his dead body and attaches it to a larger, seashell-like body with tentacles dubbed Mad Nautilus. (Interestingly, this is the part of the battle where the traditional "WARNING!" light shows up.) Despite his protective shield, Mad Nautilus was eventually defeated by X.
 * Design is a reference to Numberman.exe from the Battle network games and anime with the large pod-shaped dome on his head, as well as the multi-colored yellow and green bands on his legs. His coat-tails also appear to be inspired by Chinese formal-wear.