The first novel in Peter Clines' bestselling Ex series.
(description from bn.com)
Stealth. Gorgon. Regenerator. Cerberus. Zzzap. The Mighty Dragon. They were heroes, using their superhuman abilities to make Los Angeles a better place. Then the plague of living death spread around the globe. Billions died, civilization fell, and the city of angels was left a desolate zombie wasteland.