A dullahan, commonly known as the headless horseman, is from Irish folklore and mythology. They appear to people riding on a horse while carrying their own head.

You commonly see a dullahan drawn with knight armor or with a replacement head such as a skull or jack-o'-lantern.

Removing headless also allows you to replace the head with these:

Pumpkin head + jack-o'-lantern

Flame head / flames

Skull head

Smoke

Allows the head to be carried like the example images, also works with the tags above:

Detachable head + detached head

Holding head