Zombies are reanimated dead and mindless creatures; decaying corpses with a hunger for any type of human brains. They are the main (and more or less, only) enemy within Plants vs. Zombies, as the objective of the game is to prevent them from getting to your house and eating your brains through the use of a myriad of defensive plants, many of which specialize in unique aspects and features. You can also defend your house with lawn mowers, automatically given to you on the first level of the game. However, in the Puzzle Mode I, Zombie levels and the Vs. Mode in the Xbox Live Arcade and Nintendo DS versions of the game, the player (one of the two in Vs. Mode) must plant zombies to overcome the defenses and reach the house to eat the homeowner's brains. This is also the same with the DS version of the game
Zombies, like their defensive counterparts the plants, are varied in strength as well as speed, and command unique aspects which need to be countered appropriately.