Sigma, formerly referred to as "Commander Sigma", is the main antagonist of the Mega Man X series. He serves as the final boss in all X series games except Mega Man X: Command Mission (where he makes no appearances) and Mega Man X8 (appearing as the final boss if the game is played on easy, and as the penultimate boss if the game is set to normal or hard difficulty, since Lumine is fought on normal or hard).

The first Reploid created by Dr. Cain, Sigma was considered the finest of the Reploids and was the first leader of the Maverick Hunters; peace-keeping Reploids who defend humans against their renegade counterparts. Although he was once honorable, Sigma unexpectedly goes Maverick in the beginning of Mega Man X and rebels against humankind. He defects to the Mavericks and assumes the role of their leader. Under Sigma's command, the Mavericks grow into a legion dedicated to the extermination of the human race. Sigma instigates many of the destructive Maverick Wars, with the Maverick Hunters existing to crush Sigma and his minions.

Although he has been destroyed countless times, Sigma's programming always survives and builds himself a new form, ready to menace the world once again. It is implied that he grows more insidious and vengeful with each transformation, with each successive plan becoming more and more desperate and aggressive. His primary enemies are X, Zero, and more recently, Axl.

Class: Generalist

No strengths or weaknesses against any class.


Reploid - immune to Bleeding, Poison, Diabetes, Bio attacks, and Fried Circuits

Wicked Ways - chance to change to a target's counter-class before attacking

Relentless - immune to Stun, Cower, Exhaustion, and Prevention effects

Defensive stance - chance to block attacks, taking decreased damage



  • Slashing Energy Melee
  • One enemy
  • (special) High Crits - high chance to crit
  • (special) Ignore Defense - ignores the defense stat and penetrates shields
  • (enemy) Tenderized - takes extra damage from slashing attacks

Head beams

  • Ranged Energy
  • One Enemy
  • 5 hits
  • (enemy) Lock-On - taking extra damage from ranged attacks

Adamantium Claw

  • Slashing Melee
  • One Enemy
  • (special) Hemorrhaging Attack - causes all applications of Bleeding to trigger
  • (special) Adamantium - ignores the defense stat, but not shields
  • (enemy) Bleeding - takes damage each turn and when attacking

Electric Spark wall

  • Ranged Electric Energy
  • All Enemies
  • (enemy) Static Charge - nearby electric attacks may chain to this target, causing extra damage.


  • Ranged Fire
  • One Enemy
  • (enemy) Burning - takes damage each turn. Defense reduced.

Shield Toss

  • Ranged Vibranium
  • All Enemies
  • (enemy) Pressure Points - causes either Weakened, Exposed, Dizzy, or Slowed.


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