There are many datapacks out there that add extra mob heads, but none of them particularly suited me. The drawbacks were that most of the datapacks made for the recent versions of Minecraft utilized the new textures, which just doesn't work for me.

Time's Mob Heads adds mob heads for every mob in the game (sometime multiple) as seen in the pictures above. It also adds a few easter egg heads to dungeons & Mansions.

For the future:
  -More Dungeon types (endcities, desert temples, etc) will have heads
  -All post 1.13 heads will receive new textures based off TDA (Time's Developer Art) in the future
  -Will Update the pack for future Versions


(I may Have missed 1 or two mob heads in the picture, but I assure you that they're in the pack)