The history of the Zombie Walk is shrouded in ragged, smelly mystery. Some believe the first one took place at a 2001 film festival in Sacramento. Others think it was first conceived for the 2003 Toronto Halloween celebration. Whatever their origin, Zombie Walks today let loose hundreds of staggering undead to (lightheartedly) terrorize cities while raising money for charity and this Sunday, Charleston will join in on the brain-devouring fun. Starting at 4:30 p.m. scores of Charlestonians dressed up as the living dead will gather in Marion Square. From there, the crowd will lurch and shamble down King Street in search of fresh brains and good times. “We have zombie dogs, babies, brides, Star Wars. Anything goes,” says organizer Cassandra White. The funds raised will benefit MUSC Pulmonary Hyper Extension Program and Camp Happy Days, which sends young cancer patients to summer camp.