"Then we must use soldiers who do not have minds," replied his companion.
"Alright then, I'll send in the latest intake from West Point."
"No, you military moron! I meant robots!"
This trope is about any Robot that is built for the intent purpose of participating in a war as a combatant. These machines either supplement soldiers as a part of a battle force, or replace them entirely. They can be anywhere on the Sliding Scale of Robot Intelligence, but generally stand between 1 and 3 on the scale. Obviously, these robots are not Three-Laws Compliant, since they must be able to violate the First Law on a regular basis. This does not necessarily mean they are psychotic mass murder machines, though depending on who built them and why, they easily could be.
The distinction between this trope and Mecha-Mooks is that Mecha-Mooks are, well, Mooks. By definition, Mooks are disposable, mass produced bad guys with few or no special attributes that only exist to be easily destroyed by The Hero. So while robot soldiers can be mooks, there's no law that says "all fighting robots are mooks". A robot soldier can easily be anything from a mook, to an implacable killing machine, to the hero of a story. You'll see them often in a Robot War setting.
A REMINDER: This trope is for soldiers that are also robots, not simply any machine that is able to fight. The robot must either be a part of a military unit, or be specifically made to serve as part of a military unit, or they are not this trope.
- Attack Drone
- Grey Goo (when nanotechnology is used as a weapon)
- Mechanical Monster
- Sapient Tank
- Sentry Gun
- Spy Bot
- Surveillance Drone
- DC Comics' J.A.K.E., the G.I Robot.
- The Outer Limits (1995): In "I, Robot", the robot Adam was created by Dr. Charles Link as an experiment. When Dr. Link lost his funding, he was forced to find alternative sources of finance. To that end, he entered into business with a defense contractor who wanted him to create an army of robot soldiers. Adam was to be the prototype. When Dr. Link attempted to erase his memory files, a malfunction caused Adam to reactivate and he killed his creator.
- An important part of the backstory of Cave Story involves a war, in which an army that was sent to exterminate the Mimiga creatures living on a remote island. Though it's not immediately obvious, the player character is one such robot. Initially, he meets several NPC's who wonder if he's "a soldier from the surface". Then Professor Booster clarifies that he is a robot soldier. Shortly after, you meet Curly Brace, another robot and a veteran of the same war as him.
- In LBX/Danball Senki: While the Innovators use LBX robots, the Black Intelligence Division and the Red Military Division train their soldiers to use LBX efficientalally to the point where they can stage numerous terrorist attempts, seige an assualt at the end of Artemis, and engage in a huge LBX war between them and the Seekers during the attempted siege on Tiny Orbit.
- Fallout has had two robot armies so far. The robot armies controlled by the Calculator in Fallout Tactics: Brotherhood of Steel, and the Synths controlled by the Institute in Fallout 4. The pre-war USA also had several models of robot soldiers supplementing their human army, many of which roam the wastes killing anything they encounter after two hundred years of decay. Of course, only their Morality Chip tends to be damaged, you can expect their movement sytems, weapons, and Self-Destruct Mechanism to work like new.
- Mega Man X: Some Reploids of the verse end up betraying humanity and became destructive for one reason or another, called "going Maverick". In response to that, Doctor Cain formed the Maverick Hunters, an organization filled with robot soldiers to fight these Mavericks. They're put into distinct units such as "Marine Unit" or "Arctic Unit" to cover activities in different areas.
- Overwatch takes place after a massive war between Humanity and their Omnic creations. One of the playable characters is a former frontline combatant for the omnic side.
- Ratchet & Clank always features hordes of robot soldiers. While there are usually organic fighters in there as well, they will be vastly outnumbered by robots on both sides of the conflict. A notable case of this is the Galactic Rangers in the third game.
- In Stellaris, with enough research, robotic armies and android armies can be built for either planetary defense or invasion.
- Team Fortress 2 has Mann Vs. Machine mode, which pits six players against hordes of their robotic counterparts. The robots are more or less the equals of the base players, but are disposable and expected to die in droves anyway because their AI is pretty bad and the human players have tons of purchasable powerups. There's also a slightly-too-literal example in the Robot Soldier, which, thanks to using the Soldier's existing voice lines, comes across as a giant Cloud Cuckoolander Robotic Psychopath.
- Dark Forces revolves around the Galactic Empire conspiring to put a line of these into production: the Dark Trooper. Far from being easily-mown-down cannon fodder like the B1 battle droids, Dark Troopers are hulking, armour-clad brutes with weapons to match.
- The titular Transformers are autonomous robot soldiers fighting an ongoing war against their Always Chaotic Evil counterparts.
- In Samurai Jack, the overwhelming majority of Aku's military forces consist of expendable war robots. The most common of them are the insect-like Beetle Drones. Some of Aku's mercenaries and bounty hunters are more humanoid variants, including the morally conflicted assassin X-49.
- Truth in Television: Military robots are widely used for combat and non-combat purposes. While aerial combat drones are likely the most well known example of this, Wikipedia has an entire list of them. Indeed, since risking one's life in a war is one of the most obvious unpleasant tasks that humans would be likely to hand off to a robot to do instead, Asimov's First Law isn't looking very likely at this point.