GrimPhantomon is a Ghost Digimon whose name is derived from the English word "Grim" and the mythological Phantom and whose design is derived from the mythological Reaper. It holds a gigantic sickle and chain. It is a higher class of Ghost Digimon compared to Bakemon, so when a person is possessed by GrimPhantomon they are in their last moments, and it comes upon them when they die completely. There is a crystal shaped like an eyeball hanging from its neck, and similar to Mammothmon's crest, it is able to foresee everything with its power of clairvoyance, in order to perceive those that are close to death. It is said that the interior of the cloth which conceals its body leads to a separate dimension from the Digital World.
In Ultima, GrimPhantomon are skilled assasins in the Nightmare Soldiers division of the Org's D-Minion Army. They are usually sent after high-level targets, and reap the souls of their victims to deliver back to Padro Lodo for experimentation.
They are a natural digivolution of Soulmon and will digivolve further into MetalPhantomon or Shinigamon.
Shadow Scythe (Soul Chopper): Cuts even the opponent's soul to pieces with its gigantic sickle and chain, completely annihilating the soul.
Words of Death (死の宣告 Shi no Senkoku?, lit "Death Sentence"): Kills an opponent instantly with a word of death.
Diabolic Star: Calls dark energy into the weighted chain end of its sickle and chain and slams an opponent with it.