Sigma Head (シグマヘッド Shiguma Heddo) is the boss from the Opening Stage in Mega Man X5. He wounds the character opposite to the one the player chooses (he will destroy X's Fourth Armor if the player chose Zero, or destroys Zero's buster if the player chooses X) and then hides inside a statue under construction. It's a giant head of Sigma that releases small energy spheres from its mouth or energy spheres from its eyes. He can also attack by ramming the character across the screen. After losing half of his energy, he will also fire large energy beams from his mouth. His only vulnerable area is the cannon's lens that only appears when he opens his mouth to attack. After this boss is destroyed, Sigma's real plot is revealed.
After X or Zero have defeated him, they discover that Sigma lost to them on purpose so that he could cover the entire Earth with the Sigma Virus with the resulting explosion.
The Sigma Head appears in the Rockman X5 manhua serving the same role as in the game, only fighting both X and Zero.
|Mega Man X5|
|List of Mavericks|
| Crescent Grizzly (Grizzly Slash) • Tidal Whale (Duff McWhalen) • Volt Kraken (Squid Adler) • Shining Firefly (Izzy Glow)|
Dark Necrobat (Dark Dizzy) • Spiral Pegasus (The Skiver) • Burn Dinorex (Mattrex) • Spike Rosered (Axle the Red)
|Sigma Head • Magma Dragoon • Dynamo • Shadow Devil • Rangda Bangda W • Zero • Mega Man X • Sigma|
|Mega Man X's Special Weapons|
|Crescent Shot • Goo Shaver • Tri-Thunder • Flash Laser • Dark Hold • Wing Spiral • Ground Fire • Spike Ball|
|Zero's Special Techniques|
|C-Sword • F-Splasher • E-Blade • C-Flasher • Dark Hold • W-Shredder • Quake Blazer • Twin Dream|
| - Mega Man X -|
Fourth Armor • Falcon Armor • Gaea Armor • Ultimate Armor
- Zero -
|Hunter Base • Zero Space|
|Walkthrough • Parts • List of Enemies • Eurasia • Enigma • Space Shuttle|
Damage Data Chart (X) • Damage Data Chart (Zero) • Game Script (X's story) • Game Script (Zero's story)