Source: Hellknight Hill, pg(s). 90
A hellcrown occupies the helmet it wore in life, from which he shadow of the Hellknight's spine dangles.
If a decapitated Hellknight's corpse is unattended, a hellcrown can manifest hours after death, or days if the Hellknight fell in battle. Most hellcrowns retain no memories or personality from life, except a few particularly tragic ones who might hold grudges against those whom they blame for their death. Hellcrowns from different Hellknight orders possess different abilities reflecting their order's principles and discipline.
Hellcrowns haunt the site where they died and kill anyone that they encounter, consumed by a desire to enforce the Hellknights' merciless order through cruelty.
Hellknights view hellcrowns with both respect and disgust, considering those individuals to have been spiritually resolute but lacking in competence.