Ecology: A concrete zombies are created when those with a karmic debt to pay are murdered by being encased in concrete. Triad gangsters in Hong Kong (as well as Mafia types the world over), like to dispose of unwanted bodies (still living or not) by dumping them in freshly poured concrete foundations. Most of the time this means the unfortunate victim is gone forever. But ever now and then, the would-be corpse has a past debt to pay. At some point in their life—either this or a past one—they drowned someone, and now need to pay for their crime.
Once encased in concrete, these people transform, melding flesh and bone to concrete and rebar. The process takes about a week, and once complete, the new concrete zombie will rip its way out of its former tomb and goes hunting. They seek powerful sources of chi, such as is found in sorcerers, many martial artists, and the enlightened, and will kill anyone and everyone in their path to get it.
Personality/Motivation: A concrete zombie desires chi and that’s it. They cannot be reasoned with, commanded, or persuaded to do anything other then devour chi. They aren’t totally mindless (many can speak, if only just), but have only the most basic of needs and desires.
Powers/Tactics: Concrete zombies attack by Grabbing a foe and either crushing the life from them, or ripping into them with teeth made from stone and rebar. As a concrete zombie is nigh-on invulnerable, they tend to ignore most threats, but if sufficiently damaged it will tear into the nearest source of concrete and steel to repair itself.
Appearance: A concrete zombie is a horrific combination of flesh and stone. It may wear the ragged remains of the clothes it was entombed in, and will have teeth of broken stones and scrap metal, bones of rebar, and muscles made from slabs of concrete. When it moves it sounds like concrete grinding together, clouds of dust follow it, and flies and mosquitos issue from its mouth, usually because its belly is full of stagnant water and rotting meat.
Designer's Notes: Concrete zombies are found in the Feng Shui supplement Blowing Up Hong Kong. They are pretty powerful and probably don’t need much alteration to pose a threat to most groups of PCs. I could see using them in a really weird Post-Apocalyptic Hero game (especially one with the supernatural in play), an Urban Fantasy game, or even a Champions game.