Axl

Axl (アクセル) is one playable character from the Mega Man X series, and having an important role in two of the games he's appeared in so far. He has a very special ability called Copy Shot, which allows him to disguise himself as certain non-boss enemies. In Mega Man X: Command Mission, Axl's Action Trigger, a special command introduced in the game, allows him to turn into defeated bosses such as Wild Jango, Silver Horn, Mad Nautilus, Mach Jentra, Incentas, Depth Dragoon, Rafflesian and Ninetails.

In Mega Man ZX Advent, a Biometal called Model A appears as the only usable Biometal in the game, possessing similar appearance, weapons and shapeshifting abilities. However, the game states that it is instead named "Model Albert", and the biometal seems to instead be an unofficial tribute to the character.

Personality
He is cocky and has a sense of humor. Although he can be whiny when there is nothing to do which can get on X and Zero's nerves, Axl is kind-hearted and always cares about others. He always brags about how he is one of the best and this always gets himself into trouble.

Mega Man X7
In Axl's debut, he was a member of the bounty hunter syndicate, Red Alert. However, after questioning their methods, he escapes their base, and was "captured" by Zero. When the conflict between his old group and the Maverick Hunters began, Axl felt himself responsible, since Red Alert is challenging the Hunters for his custody. In order to make up for his mistakes, he joins forces with Zero and the Hunters to stop Red Alert, although they were initially reluctant to let him join. It was through Axl and Zero's combined efforts during the conflict that X came out of retirement to fight again.

Together, the three infiltrate Red Alert's base of operations, and confronted the leader, Red, himself. After defeating Red, the Hunters learn that Sigma is at it again, manipulating Red Alert from the shadows. Even after defeating Sigma, twice, he comes back, and punches Axl through a wall. Sigma also swore to have a new form when he does return. Red reappears, and just when Sigma is assumably attempting to possess him, Red uses Axl's pistol to blast Sigma out of the palace through a window. It turns out that "Red" is actually Axl copying his DNA to trick Sigma into defeat. Together, the three, X, Zero and Axl, escape the crumbling palace.

Mega Man X8
Axl joins X and Zero in the forest outskirts of the Jakob Orbital Elevator, investigating a crab-like Mechaniloid. This time around, Axl is now a full member of the Maverick Hunters and was trusted by both X and Zero.

After the first mission, the three encounter (Axl for the first time) Vile, who kidnaps the director of the Jakob project, Lumine. After this incident, a series of Maverick attacks begin, all revolving around the involvement of New Generation Reploids. It turns out that Axl is a prototype of these Reploids, since they have the same copy chip as he did. Some of the Reploid Mavericks think of Axl as a traitor, with him siding with "Old" Reploids. The mastermind of the incident is revealed to be Sigma again, and the three Hunters chase him to the his palace on the Moon. However, after Sigma is defeated (presumably for the last time), Lumine reappears, saying he will take over from Sigma. Axl and his friends defeat Lumine, but  the latter has one last trick up his sleeve: something lashes out of the lifeless shell of the villain and hits Axl, before finally being destroyed by X and Zero.

When the group begins their descent back to Earth, Axl is carried on X's arms, and is borderline conscious. In his cracked forehead crystal shines a fragment of what Lumine hit him with, although the implication of this is unclear.

Mega Man X: Command Mission
Axl comes to Gigantis a short time after X and Zero did, believing that his copy abilities may have originated there. He joins X's party midway through a mission to infiltrate Mach Jentra's Ulfat Factory.

Trivia

 * Axl's Action Trigger in Command Mission follows the Mega Man tradition of copying Boss attacks, as he temporarily transforms into a defeated Boss and uses that Boss's attack.
 * With the Mega Man Zero Official Complete Works revealing that the Orbital Elevator in X8 is part of the canon (and by proxy, Mega Man X7 and Mega Man X: Command Mission), some fans still speculate if Axl himself is still involved. If so, then the question is on whatever happened to him during the Elf Wars.