A Dolahan (sometimes spelled Dollahan) is a blackened suit of armor possessed and controlled by a demon. They can be killed by ordinary means, but are extremely strong, magically powerful, and never require rest.
Dolahans are mentioned in The Inclination to Destiny(Story) and The Reunion of the Eighth Power, as well as The Path to Ascension(Story). They are also a unit in mage Wars RPG and a card in the Mage Wars Card Game.
In The Reunion of the Eighth Power, a man is also seen wearing "Dollahan Armor" - the armor can be retrieved from a defeated dollahan and worn. It gives the wearer drastically enhanced speed and endurance, as well as unnaturally long life. It also cannot be removed, eventually growing into the wearer's flesh.
Anyone who puts on Dolahan armor will one day die in it, transforming first into a Thusen Draugr, and, eventually, when the flesh has rotted away entirely, back into a Dolahan.