The Femme Pyro, also called the FemPyro, is a very popular fan-made intepretation of the Pyro from Team Fortress 2. This article uses The_Fanciest_of_Pants' Femme Pyro Redux version, the most mainstream and advanced version, as a reference.
The Femme Pyro is a female mercenary, working for either the RED or the BLU team. She wears a black gas-mask that completely encases her head, a blue/red fireproof-jumpsuit that looks latex/leather in texture, black knee-high boots, elbow-high gloves, and a harness. Her age and nationality are unknown but according to this post, the regular Pyro's height is roughly 5'9, so Femme Pyro's couldn't be too far off. Her suit makes her jiggly boobs and ass pop out to give players the full gravity of how massive they are. A very popular tweak to the skin removes the pants-part of her jumpsuit and makes the upper-body-part more of a leotard, to show her white, tanned ass and hot thighs.