Icon of Sin

The Icon of Sin (aka Baphomet and Gatekeeper) is a monster which first appears in Doom II. It appears three more times in Final Doom, and Doom II RPG, where it appears in two forms VIOS (Virtual Icon of Sin), and a physical Icon of Doom (that spawned the VIOS virus). It makes yet another appearance in Doom (2016) where it is given a backstory. It's final appearance is in Doom Eternal, where its full form is seen.