Aspiring extras for The Walking Dead were required to attend a rigorous "Zombie School" where they were evaluated on their ability to perform a loose, "drunken" stumble while staying silent. Executive producer Greg Nicotero selected the winners based on their physical characterizations and their ability to avoid stiff, stereotypical movements in favor of a more realistic, predatory shuffle. Credits: NBCUniversal, AMC Networks, Skybound Entertainment | History In Pictures