Zombies

Zombies are pretty much your only allies in this game. Whenever Stubbs kills anybody by eating their brains, hitting them to death, or by a gut grenade, the person that was killed will reanimate as a zombie. Zombies will frantically attack any living person they see and are not that smart, which is shown when they completely ignored the landmines in front of the soldiers later in the game, and subsequently blew themselves up. They will always rush straight at the people even if they are out-manned and out-gunned. They are somewhat tough however, since a single zombie can take on two and maybe 3 armed police officers and win, but they will often get mowed down by the more powerful and more damaging enemies later in the game. Stubbs can get zombies to follow him by whistling if the zombies can't see anyone within their sight range, and as soon as they see a living person they will immediately rush the person. The zombie's greatest strength is in numbers, as large hordes will literally tear through most resistance with ease. An easy way to get large hordes would be to eat one person, let him reanimate, eat another person while he eats someone else, and keep repeating until you have amassed a sizeable horde. Sometimes when you are low on health it is smart to let the zombies go ahead of you and eat and infect the people for you. Zombies are capable of eating people's brains when they are stunned from a flatulence blast or when they are weak and can also just hit and claw people to death, both of which will also infect and reanimate the victim. Note, if people don't die from the direct actions of a zombie, for example, getting shot from a person possessed by your hand, friendly fire from their allies, or getting hit with a vehicle or from the gun of a vehicle, they will NOT reanimate and become zombies, so choose carefully when possessing people or in the turret of a vehicle, it is usually best to kill or at least weaken the ones with powerful weapons, and to leave weak targets like civilians and police officers alive so they can be transformed into zombies. When armed people reanimate, they drop their weapons and won't use them, not even the ones wielding melee weapons.

Trivia

 * If zombies do nothing, they will not only moan, but also will perform dances from Michael Jackson's Thriller.
 * You can push them forward and whistle to attract their attention to move them in the right direction. By pushing a zombie right to an enemy (without a helmet) you allow him/her to immediately start eating the enemie's brain.
 * Even though they aren't very smart, they become passengers of vehicles, come into charger boxes, dance not bad and etc.