The Imperial Guard (also known as the Astra Militarum) is the primary fighting force of the Imperium's military. They are composed of unaugmented humans, unlike the Space Marines, with many planets being home to various specialized regiments. Compared to most Xenos and Chaos threats, an individual guardsmen is quite weak; however, the Guard's strength lies in its numbers, using overwhelming firepower and vehicular support to suppress the enemy into submission.
The Imperial Guard was originally intended to only serve as auxillaries to the Space Marines during the Great Crusade, as their arms were generally inferior and were less likely to survive direct combat. But after the Horus Heresy and the breakup of the Space Marine Legions, the Imperial Guard grew to fill in the gaps. Armed with weaker lasrifles and flak armor, an average guardsman isn't expected to last long, especially under the guidance of incompetent or uncaring officers; particularly if the company's Commissar feels the need to discipline troops through executions.
Guardsmen get very little respect, as they've earned the dubious nickname of "flashlight guys" or "living flashlights" due to the relative ineffectiveness of their lasguns and their ultimate expendability. In most episodes they appear as generic pawns that get brutally murdered or otherwise abused by both the enemies of mankind and their own superiors. They get a more in-depth depiction in the episodes of BRO TRIP 40,000.
- Cadian Shock Troops - from the fortress world of Cadia, a strategic planet that blocks Chaos forces from leaving the Eye of Terror. Cadians will often be veterans of many conflicts and sent around the Imperium to assist elsewhere. Most generic regiments and planetary defense forces are equipped similarly to Cadians, but often lack the same intense training or experience.
- Armageddon Steel Legion - a heavily mechanized regiment from the Industrial world of Armageddon, they have fought three massive and consecutive land wars on their home planet.
- Death Korps of Krieg - a regiment of vat-grown soldiers from the Death world of Krieg; as punishment for a previous rebellion, every citizen must serve as expendable troops. They are particularly effective in trench and siege warfare, and their primary strategy is to throw as many men as they can at an objective. The Emperor, not knowing the history of the Kriegers or their obsessive nature, forgave them in reply to a letter that had been sent to him and told them to continue fighting for the glory of mankind.
- Catachan Jungle Fighters - bush fighters from the Death world of Catachan, they are formidable in close combat and ambushes, having grown up on a planet where absolutely everything will kill you. They appear in Episode 1 of BRO TRIP 40,000. Corvus Corax complains that the only reason that the Catachan Jungle Fighters' talents are wasted on the Imperial Guard and not the Space Marines is bureaucratic politics, as well as the ridiculousness of them only fighting half-naked and with minimal supplies. Nonetheless they are very effective at their jobs, particularly the legend known as Sly Marbo.
- Tempestus Scions - many of the more famous regiments have their own dedicated Stormtrooper forces, but for everyone else, the Tempestus Scions are the primary source of elite soldiers. They are typically trained from a young age to serve in specialized units as heavy shock troops. The Inquisition prefers to use Scions for most of the gruntwork. In TTS the Scions are named after various British WWII tanks.
- Vostroyan Firstborn - Vostroya's tradition of sending all firstborn children to the Guard has produced a very large and experienced regiment, where equipment are highly prized family heirlooms. In a video by Karl, the Vostroyans use Gopnik stereotypes and dance into battle to hardbass music.
- Attilan Rough Riders - Attilans are primarily a cavalry force that still fight on horseback using special lances. They have an obsession with drinking out of skulls and are almost always on top of their horses, even when indoors or piloting aircraft.
- Jopall Indentured Squadron - Jopall’s population are indebted to the planetary government from birth, and as such many citizens join the Indentured Squadrons to pay off their debts. Their commissars will frequently fine then to keep them in debt. Elite "Asstart Spaggle MensTM" are "Pay-to-Win" Gland Warriors with a bizarre armor mashup based on Master Chief (Halo), Samus Aran (Metroid Prime), Buzz Lightyear (Toy Story) and Terran Marine (StarCraft), and are most definitely not copyright-infringing on Astartes. The Indentured Squadrons were able to overthrow their planetary government with the help of Corvus Corax, and hired themselves out as mercenaries so as to earn hush money in case anyone investigated their planet. 
- Commander Militant of the Imperial Guard
- Ollanius Pius
- Sly Marbo
- Hobo Guardsman
- Colonel 'Iron Hand' Straken
- Gunnery Sergeant ‘Stonetooth’ Harker
- Tempestus Scions
- Mogul Kamir
- Ciaphas Cain
- Terrified Guardsman