Amazing but true, a real and documented case of a zombie has been the subject of legend for many years in Haiti. It seems that in 1962 a Haitian man, Clairvius Narcisse took ill and was taken to a hospital in Haiti in a coma-like state where American-trained doctors pronounced the man dead and pulled a sheet over him. The next day he was buried. But soon grave robbers stole his body, and when his coma eased and he regained movement they beat him and drugged him and turned him into a sugar plantation slave for 16 years until he was finally able to escape.
More documented cases exist, including tourists who were drugged and turned into plantation slaves working for years in some some sort of drug induced stupor, unable to leave of their free will.
These cases may not be the same as your classic George Romero NIGHT OF THE LIVING DEAD zombie feature. Yet, they are strange and true.