The new character in Borderlands 2, the Mechromancer has 15 available heads as of now, this tutorial will teach you how to unlock the "Digitized Death" head.

Step 1. You must be past the part in the storyline where you kill the bunker

Step 2. Travel to thousand cuts

Step 3. Head up to the BNK3R

Step 4. Once it spawns, kill it

Step 5. Check the loot, if you don't recieve the mechromancer head, save and quit and kill the BNK3R again

Step 6. Continue killing until the head drops.