Mob Head Drops

Killing mobs may cause them to drop their head.
Every mob has one or more collectible heads. A head will only drop when a player kills a mob, not when they die to environmental damage.
This is a complete list of all heads available in the 1.20 cycle, including the rarity level. It can also be viewed as a spreadsheet to copy if you wish to collect them yourself! Click here for access.
In cases where there is a spare line in the name column, it indicates there are multiples of head rarities for that mob, as shown here using llamas as an example.
Fun Fact: The only mob with a Very Rare head is the Drowned.