Zombie

The Zombie is an undead creature, probably the most common undead creature, that are either in mobs or a single zombie serving one master.

Origin & "Old" Zombie
The Origin of the zombie is believed to be in Haiti. Voodoo priests would perform a ritual of some sort involving a powerful neurotoxin. This was usually done to a living person, putting them into a trance-like state. Though many cultures have their own version of a zombie, the Haitian zombies serve one master and do his/her bidding. An "old zombie" is usually one zombie that does only one thing: eat brains!, and was basically the classic zombie until the "mob zombie" took over.

"Mob Zombies"
Some zombies travel in mobs such as the zombies in Dawn of the Dead or those in the game series Left 4 Dead. These zombies are extremely dangerous and usually happen in a "Zombie Apocalypse" doomsday scenario. This is when an infectious disease turns people into zombies and often happens worldwide. Usually a blow to the head will kill these zombies. Mob zombies usually move quickly and in large groups. The disease is spread by zombies biting or scratching living humans until no one is left. ALSO ZOMBIES ARE NOT DEAD! THEY ARE ALIVE UNTIL THE BRAIN DIES!