The Lasgun, also sometimes referred to as a Lasrifle, is a directed-energy antipersonnel weapon used by the military forces of the Imperium of Man, and it is the most common and widely-used type of laser weapon in the galaxy. It is standard-issue for the Adeptus Mechanicus' cybernetic Skitarii infantry, all Astra Militarum rank-and-file infantry and most junior Astra Militarum officers. Lasguns are reliable, easy to maintain and to produce, and are readily available on most Imperial worlds.

A Lasgun has a longer range than a Laspistol, but is nowhere near as powerful as a Lascannon nor does it possess the rapid-firing qualities of the Multi-Laser or the Hellgun. Though not as powerful as kinetic projectile weapons such as the ubiquitous Bolter, the lower cost of production, the lack of a requirement for ammunition production and resupply make the Lasgun the best choice for the large forces of the Imperial Guard. The Lasgun uses a small portable capacitor power pack to produce a focused pinpoint laser beam which is strong enough to take an ordinary human arm off with one shot but is not as effective against the more durable alien bodies and stronger types of personal armour. A Lasgun's beam also cauterizes the wounds it inflicts due to the immense heat given off by the shot. The Lasgun is effective when used en masse, but considerably less effective when used alone.