Zombies are enemies from the Thing Thing series of Flash games.
Zombies, first appearing in Thing Thing Arena as a special survival mode, are Thing Things risen from the dead. They run abnormally fast, attack in a barraging fashion, and take a decent amount of damage before dropping, their bodies are grossly decompose, organs and even bones being exposed. They return in Thing Thing 3 in the games own Zombie Survival mode mostly unchanged, except available weapons have changed. Thing Thing Arena 2 depicts them again, but with alternate weapons once more, and more roaming area to fight them in. In Thing Thing 4, they are given an implied backstory. Systems Corp. (an antagonist organization responsible for the creation of the protagonist, experiment 154, who is the ultimate artificial life form, and his angry, obsolete, "older brother", experiment 153, who held that title prior to 154's creation) started a project to resurrect the dead, that, going by the results, did not go entirely as planned.