Burn Dinorex (known as Mattrex in the original American release) is a Reploid boss from Mega Man X5. He was originally part of Repliforce's disaster response division, and was one of the few Repliforce officers to survive the coup. When the Sigma Virus was spread worldwide, Dinorex was stationed at Sunhouse Mountain in Kenya where he was guarding a stockpile of illegal weapons left over from the coup. Among the weapons was also a booster engine which the Maverick Hunters needed for their space shuttle. Dinorex had not been infected by the Sigma Virus, but he was extremely paranoid and suspected that the Hunters intended to retire him whether he was Maverick or not, and so he lashed out when X approached him. X had no intention of harming the Reploid, but because of Dinorex's violent paranoia, he was forced to do so anyway.
- Burning Tackle - Dinorex ignites all of the torches on his back and hurls himself at his opponent, usually at an upward angle.
- Inferno Tackle - An overpowered version of the Burning Tackle that creates flaming eruptions on the floor and ceiling.
- Ground Fire - Dinorex spits flames from his mouth that scatter as they hit the ground. X can copy this weapon and Zero gains his Quake Blazer technique based on this ability.
- Grand Fire - Dinorex breathes a stream of fire and sets the ground ablaze.
- Triple Fireball - Dinorex clings to the wall and spits three fireballs at his opponent.
Powerful wind currents can extinguish Dinorex's torches, making him vulnerable to the Wing Spiral and Wind Shredder.