PX-41

The PX-41 Serum is a very dangerous transformation and the main focus in Despicable 2, as Gru helps the AVL to get it back from the thief.

Lore
The PX-41 is a very dangerous mutator engineered in the top secret PX-Labs, located in the Arctic Circle. It is capable of turning any living things in the world into a purple, furry, indestructible, mindless, killing machine that is so dangerous that it can destroy anything in its path. The effects of the serum can be counteracted by PX-41 Antidote, an antidote serum that was invented by Dr. Nefario.

The only two ways to turn into a purple monster is to inject it or drink it.