Pyro

Pyromaniac, aka Pyro, is a mysterious figure and part of the Hallowers rebel band on Aedra fighting against the Combine. His identity is hidden, and nothing is known about him except that he had a troubled past and that he has always like spiders and fire.

He owns a custom-built flamethrower powered by Kerus gel that can incinerate refined durasteel within seconds. He wears a mask and inflammable armor.

Background
Nothing is known about Pyro's history except for a few things.

He was formerly part of a criminal/terrorist association, currently unspecified as to which exactly. During his time there, he was known as Nightflare and used a different suit and weapon, which were black and green rather than red and black as his current garments are.

It is probable he was a killer because he apparently doesn't hesistate to slaughter hundreds during the Hallowers series.