Doom has three main timelines, each with unique interpretations of the Doomguy and his mission. The original series focuses on Mars and Earth's invasion by hellish creatures. The reboot introduces the Doom Slayer, a warrior from ancient times who combats demonic forces on Earth.

The Doom series has been a high-profile franchise since the original installment in 1993. While not the first first-person shooter game, Doom ushered the genre into the mainstream in brilliant, gory fashion. Since its debut in the early 1990s, Doom has spawned numerous sequels and spin-offs, as well as films, books, and many other forms of media. Naturally, the story of Doom has branched off into numerous directions, creating its own universe of lore in which the Doomguy has been reimagined many times over. With Doom: Dark Ages recently announced, now is a great time to get the story straight.

If excluding all media outside of the video games,...