The Forgotten Ones' form is an echo of the original Lost Soul's shape in the classic Doom games, replacing the reinterpretation in Doom 3. They are exclusive to the Resurrection of Evil expansion pack.
It is a flying skull with two demon horns, when it floats a flame ejects behind it.
The Forgotten One's attack is almost identical to that of the Lost Souls in Doom 3; its only attack consists of flying towards its enemy and biting. However, their charge attacks are slower and there appears to be a slight lag when they initiate their charge attacks. Also, Forgotten Ones do not moan and scream upon detecting the player.
Due to the lack of melee weaponry and their smaller size, these enemies are much more difficult to eliminate than the original. However they are also more tolerable than the Lost Souls in Doom 3, as their attacks are more predictable and easier to dodge. As in Doom 3, the use of the chainsaw or weak weaponry can result in immediate death, however this incarnation has the potential to withstand a standard shotgun blast from mid-range. On the other hand, the player has a new advantage over them; they can be caught by the Ionized Plasma Levitator (aka the Grabber). Once grabbed, they can still potentially fight the beam and hurt the player, so it is best to immediately shoot them away, which disintegrates them.