The Iron Imprisoner is a large, armored Unversed with four different forms. In its first form, the Iron Imprisoner I's lower body is locked in a black gibbet with silver highlights and several black, diamond-shaped gems set in it. Its arms, which are covered in black armor with two blue gauntlets, are bound by four red chains. Only its head, encased in a helmet that is light grey on its right half and grey on its left half, is free to move. It has jagged, black horns on either side of its helmet, though they are not of the same shape. The right horn is somewhat straighter and more horizontal, while the left horn hooks upward sharply. Its eyes are red, set in an angry expression, and slightly uneven.
The Iron Imprisoner II is identical to its first form, save for two significant changes. The Iron Imprisoner's chains are gone and its arms are free, making its gauntlets and red collar clearer. It is also now wielding a large, red and black hammer with spikes on its head. The handle of this hammer is tan and the pommel is a black spike. The head of the hammer can conjure fire.
The Iron Imprisoner III is now free of its gibbet, exposing its grey legs. Both of its feet sport black bands with blue highlights on them. Its collar is much smaller and the grey breastplate it wears is now clearly visible.
The Iron Imprisoner IV sports a radically different coloration than its previous incarnations. Its armor is now much darker, mostly colored in shades of black and dark grey. Its lower legs are light grey and the tips of its feet are red. Its gauntlets are now red and black, and its breastplate sports blue highlights. The Iron Imprisoner’s helmet is now uniformly colored black and its eyes have changed shape, though they are still set in an angry expression. On each form, the Unversed insignia is on its back.
In Kingdom Hearts Birth by Sleep Final Mix, the Iron Imprisoner receives a recoloration, its body is now purple, with is arms and leg are now a fuchsia color. The collars on its arms and legs are now green. Its lower body is now locked in a black gibbet with gold highlight, bound in gold chain. The hammer handle is now silver, with a gold spike. The hammer itself is now purple with green highlight. The Iron Imprisoner's helmet color is now one half black and the other half white.