Butter is a special projectile launched by Kernel-pults, although it is less common than the kernels that they usually throw. It can immobilize most types of zombies. Butter does two damage per stick, but is thrown half as often as peas are launched from Peashooters.
When a zombie is hit by butter, with the exception of Zombonis, Pogo Zombies (which still have their Pogo Stick), and Dr. Zomboss, it is temporarily immobilized. After five seconds, the butter will disappear from the zombie's head. Also in any Co-op Mode on the console versions, the player can manually butter a zombie by pressing the button (XBox 360) or (PlayStation 3), although this butter does not do any damage to zombies.
In the mini-game Buttered Popcorn, which is exclusive to the iPad and Android versions of Plants vs. Zombies, the player has the ability to freeze a zombie in their tracks with butter by simply tapping their head. Because the only offensive plant in this Mini-game are four Cob Cannons it is crucial to paralyze the zombies with butter so that the zombies do not eat the Cob Cannons.
- In the music video "Zombies on Your Lawn", there is a Zombie that has butter on its head.
- The Explorer Zombie cannot burn plants while butter is on its head.