This is the German Flamethrower unit. While he looks pretty ugly with those bottles on back and pipe in front, he IS dangerous. When he will get enough close, he will pull the trigger and try to set your troops on fire. When on fire, troops will run around, potentially setting fire to other soldiers. They will eventually die, leaving a charred body.
The flamethrower's weapon is also dangerous to both himself and units friendly to him. If he is shot in the tank, KABOOM!! His life and the lives of those around him will end in flames.
This dude is easy to kill while advancing because he moves at the same pace as other Germans, and needs to get close to your units before firing. Sometimes when he is shot, the bottles of flammable liquids on him can explode, gibbing him, and setting nearby units and dead bodies on fire. But if he gets close to a bunker and manages to fire, you may encounter some serious problems. Don't worry if your men are over 200 pixels away, he is useless at that range, but his range may sometimes deceive you.
This trigger-happy buddy will also appear in Special Weapons Blitz waves with their close friends, the Panzerschrecks.
And just so you all know...Edit
Pillboxes are not impervious to fire, nor are bunkers. Fear the German Flamer because his toy is the bane of troops in either construction. Concentrating fire on them is a should be a high priority.