Combine Zombie

http://pnmedia.gamespy.com/screenshots/phl/10266587.jpg

After the explosion atop the Citadel rocked City 17, security was breeched on all fronts, and disoriented soldiers became the latest hosts for marauding headcrabs. However, unlike any other zombie we've seen so far, Combine zombies are outfitted in the body armor of their victims, making them much tougher to take down. If they have a clear path, they'll try to ram into you upon sight with a powerful head-butt. They also still "remember" how to use their grenades, and will resort to kamikaze tactics if they take too many hits or you get too close.