Spectre (DOOM)

The Spectre is a type of demon from the DOOM video game series. This beast is an evolved variant of the Pinky, possessing the ability to render itself invisible.

Classic Series
First appearing in the original DOOM, Spectres are transparent, colourless versions of the Pinkies. Due to their transparency, they can be quite difficult to spot. Beyond that, their abilities and behaviour are identical to the standard Pinky; they have a similar hit box and health and can only attack by getting in close to the player.

In DOOM 64, Spectres initially appear as muddy-green in colour, but become translucent as soon as they detect the player. They are stronger than the standard Pinky and just as fast, quickly closing the gap between themselves and the player.

Modern Series
In DOOM (2016), Spectres are described as being genetically altered variants of the Pinky. During the initial Lazarus Experiment, the UAC captured a small number of Pinkies for experimentation. All but one specimen died during experimentation; the surviving specimen was implanted with the optic nerve of a Cacodemon, resulting in it developing low-level psionic potential. This psionic addition allowed the creature to render itself invisible. It used this ability to trick its handlers into believing it had escaped, then killed the handlers when they opened the cell and fled. It somehow made its way back to Hell (most likely brought back by a Summoner) and was able to breed with regular Pinkies, passing on its psionic traits to its offspring.

In both DOOM (2016) and DOOM Eternal, the Spectre is essentially identical to the Pinky in terms of behaviour, biting at the player as it gets in close or charging from a distance if it has a clear path. It has lower resilience than the Pinky as it lacks a head carapace.