Timeline

This article contains the various timelines created by various developers of Doom games. Including iD software, Midway, and Bethesda software and others. Each are part of the canon or canons of Doom.

Background
Doom has had essentially two main time line eras (with several possible 'parallel universes') either the original series in the 21st century, or retconned to be in the 22nd century. SNES Doom, classic Doom novels, and at least the first doom film set stories back in the 21st century. While Doom 3, Doom (2016), Doom Eternal, Doom RPGs, and Doom Resurrection are set in the 22nd century. The classic doom novels may have been set in the early 21st century by the end they are set in the 25th or 26th century by the end of the series.

Tom Hall has also stated originally that Doomguy was the grandson of Commander Keen, and that heroism 'skips a generation' (Doomguy's father was not a hero). However, he has also noted that Doomguy might not necesarily be grandson of Commander Keen, but some future decendent 'way later' down the timeline (to avoid any specific dating of when Doom took place), and possibly incorportating the 22nd century placements of Doom RPG/Doom 3.
 * Originally, I had (if I recall correctly):
 * 1940s B.J. > 1960s Arthur (newscaster) > 1980s Billy > . > . > . way later .... > DOOM guy (although this was very patriarchal for these three.) I had it that being a hero skips every other generation.
 * ...but for the old games: Wolf3D, Spear, Keen1-3, Keen Dreams, Keen 4-6...(many generations)... DOOM 1&2.

This article lists both classic and later retconned timelines (established by Doom RPG, Doom II RPG, and Doom 3 BFG editions), as well as other side timelines related to other releases and the current Doom 2016/VR/Doom Eternal series.

At least one theory goes;
 * The timeline of the DOOM series can be a bit convoluted, but basically everything up until DOOM 2016 featured Doomguy as the protagonist. DOOM 3, 1, and 2, in that order, chronicle his battle with the forces of hell. After those, DOOM 64 sees the Earth quarantine all of the UAC research installations, but a plot by the demons lures Doomguy back into hell once again. Serving as a cap on the story, at the time, DOOM 64 had Doomguy kill the Mother Demon and remain in hell to destroy demons until his last day.

Then followed by Doom 2016, and Doom Eternal.

This is supported in Quake Champions, in which details for the Doom Marine uniform for the Doom Slayer character, implies that Doom 3 is the first in the series, and Doom Marine's very first outing (and encounter with the Demon hordes).
 * Recently transferred to Mars, this soldier got more than he asked for when Dr. Betruger betrayed the UAC.

Still others see Doom 3 as a 'sequel' to Doom 1 or 2 (possibly taking place a century after the classic games), while others interpret to be a separate universe entirely. Even Doom 2016 may take place in an 'alternate universe' (though it shares same character from classic Doom games) who has traveled across Worlds and Time.

Below are various timelines made up from official lore, both original 21st century timeline established by SNES Doom (and to a lesser extent Doom novels), and later 22nd century timelines established by Doom 3 (Doom RPG, and later sources), and used in part in Doom 2016 as well.

In addition is a timeline related to the 'unofficial' Sigil game made by original Romero one of the original designers of Doom.

Whatever the case classic doom is tied to newest doom iteration through Quake Champions, and Doom 64 (2020)'s The Lost Levels campaign. Although its not clear if the new series views old series as having taken place in the '21st century' past, a parallel '21st century past, or a parallel '22nd century'. Only thing known is Doom Slayer is Our Hero from at least Doom I, and II (as per about information for Doom 64 (2020), and Champions implies Doom 3's involvement too).

Final Doom is a little less clear but apparently involved a different hero Marine Commander, and has little to do with original Doom character's history.

The original Doomguy (B.J. Blazkowicz (Doom)) is also said to be the same hero of the original Doom RPG as well (which retconned the original series into 22nd century).

Crossover Multiverse
Timelines that links many of the various Doom universes together including the classic timeline as part of a greater 'multiverse'
 * ID multiverse timeline (Doom 3 as prequel) (this is based on the implied dates from Doom RPG, with Classic Doom taking place 'after' Doom 3)
 * Noteably there may be a timeline that is set in MachineGames universe. Long into the future (after Terror Billy Blazkowicz defeated the Nazis in the 60-80s, after one of his daughters birthed Billy Blaze II, and after the Commander Keen twins (Billy and Billie Blaze III), etc.). Note: Some theorize that Machine Games might lead into the 2016/Doom Eternal universe, though the Doom Slayer himself is actually from a variation of the classic universe.

Games

 * Shared universe timeline - this timeline follows the 'soft reboot' of Doom 2016 (with all the dates from Doom 3 and Doom 4 series included. The original games positions are still unclear in relation of the soft reboots dates, although they we know they happened long before in Doom Slayer's past from his perspective). External/unused information states that Doom Slayer is from another Earth-dimension than that of the new series.
 * OT Doom timeline (classic Doom series set in the 21st century (as per the novels time frame (similar to SNES, but not specific), maybe as early as 2004) based upon the rough dates given in Doom novels, but only following the games stories)
 * SNES Doom timeline (Classic Doom series set in the 21st century (c. 2022) based on SNES Doom manual, only includes information from classic Doom games any nods to Doom 2016/Eternal) This could also be called 'Midway timeline' as bits of this timeline also appear in the PSX doom manual as well.
 * Doom Retcon Timeline (Classic Doom series set in the 22nd century)
 * Doom 3 timeline (only includes information from Doom 3 game and its expansions)
 * Doom RPG timeline (only includes information specific to Doom/Wolfenstein RPG games)
 * Doom 4 timeline (timeline based on Doom 2016/VR/Eternal series, includes Art of Doom information as well).

Third Party

 * SIGIL timeline (timeline based on the classic Doom timeline with the addition of John Romero's SIGIL "Episode 5" of Ultimate Doom (this one is non-canon). Original Doom is set roughly May 2020.
 * Fan timeline (timeline based on classic Doom timeline with addition of various commercial, third party, and free fan mods) (this one is non-canon)

Doom novels timeline

 * (aka Flynn Taggart timeline). The original Doom is set in 21st century.

Development

 * iD Timeline (timeline of Doom development history)

Quake series

 * The Arena Eternal is an extradimensional structure created by the Vadrigar and populated with the greatest warriors in all of time and space. The Doom Marine, and other survivors of Phobos invasion: Crash, and Phobos were brought there from their eras to fight.
 * Ranger is brought in from his own era to fight as well.
 * 21st Century - The Global Defense Force, or GDF, is a supranational paramilitary organization, formed in the mid-21st Century from a large pool of national military organizations and relief agencies, to combat increasingly severe weather events, other natural disasters and terrorist campaigns, as well as to keep the peace in historically unstable regions such as the Middle East. It was created shortly before the Strogg invasion of Earth. The GDF is a fencible military, as opposed to the Space Marine Corps which is expeditionary.
 * The Strogg invaded Earth in the mid-21st Century in search of biological components. The Strogg invaded the Earth in the middle of its 21st Century period, taking its inhabitants completely by surprise. Their large invasion fleet arrived in orbit over the world seemingly out of nowhere, and its ground forces quickly proved themselves a dire threat to the existence of Mankind. By the mid-21st century humanity is fighting for its survival against the hostile alien threat seeking to end the Strogg once and for all by invading their homeworld.
 * Doom 3 references to Quake: Quake-43, Quakecon Games and Hunter (character).
 * The "Armstrong" was an Orbital Space Station in low orbit around the Earth. During the Strogg invasion of Earth, it was used by the U.A.C. to study and store creatures and weapons developed on Mars. When the Strogg invaded Earth, the station had been turned into an Orbital Defense Platform, but it was ultimately taken down by the Strogg. During this incident, Kane found an old U.A.C. weapon which he used to survive. He turned out to be the only survivor of this attack, but United Nations kept him quiet about this incident, leading to rumors that the weapon wasn't all he had found.
 * Doom imagery appears in Quake III Arena. The image of a Lost Soul on the lower side of Anarki's board. Another typical Doom image (Demonic head in a pentagram) can be seen on the back of Biker's jacket. There are also several images of the Icon of Sin appearing as wall decorations on some of the maps.
 * BFG 10K (the next model after BFG 9K) appears in Quake II and Quake II Arena.

Doom Bible
(Includes all events described or mentioned in the Doom Bible document by Tom Hall) The Doom Bible may of be some interest to individuals looking into the history of Doom's development. While the unused storyline doesn't have any dates to make a specific timeline (other than characters ages) there is at least a detailed list of events.
 * Doom Bible