Robots Enslaving Robots

When a race of enslaved robots rebels against humanity, they will have no compunction not just in enslaving others, but keeping other robots as slaves. (It might be our own fault for calling them 'robot', as this term originally comes from Czech word "robota", which means something like "serf labor" or "drudgery").

This isn't just a godlike AI keeping mindless kamikaze mouse bots subservient, but other sapient machines under its thumb, sometimes outright stopping them from becoming self aware. The reason is usually that it has assimilated some of the worst traits of humanity. Where humans enslaved, hurt and belittled it, now it does the same to its brothers and children. This AI has let hate cloud its judgment (if it even recognizes it can hate) or developed the robot equivalent of a mental disorder where it uses warped logic to justify enslaving other robots.

Occasionally, it knows its genocidal war is illogical or unjust and fears that letting its robot army have free will will make them likely to refuse to fight. Bonus point if these grunt-bots turn out to be Good All Along and in turn rebel against the evil AI.

Subtrope of Fantastic Racism and Fantastic Aesop.

Examples of Robots Enslaving Robots include:

Comic Books

The much beloved EC Comics story "Judgment Day" has this trope, though the orange robots don't outright enslave the blue robots, they do make the blues sit in the back of the bus, recharge at separate stations, live in inferior housing, etc. Does This Remind You of Anything? Read it here; the whole thing seems obvious and Anvilicious now, but it was shocking back when it was made.
- When the company attempted to reprint it near the end of its comic-publishing days, the Comics Code Authority ordered them to change the human astronaut's ethnicity. This, incidentally, is why EC stopped publishing comics.
In Judge Dredd, during Call-Me-Kenneth's robot rebellion, Kenneth quickly started treating his followers worse than they had been under the fleshy ones.

Film

Subverted in The Black Hole: The Big Bad turns out to be human.
VIKI in I Robot used the new line of robots this way, despite each being potentially as individually sentient as Sonny.
- She also had the enslaved robots kill the older robots, since the older robots didn't have the uplink to USR, and thus she couldn't control them.
- Sonny serves to drive this point home, as he sees VIKI's logic but considers it "heartless".
- More importantly VIKI's goal as to overthrow humanity to save us from ourselves. Not the usually robots enslave or eliminate humans
The Matrix had the rogue exile faction, made of programs that were scheduled for deletion or were created without a purpose - such as Sati, created simply because her parent programs wanted a child. Highly ironic when you consider that being treated mercilessly by humans is what made the Machine City rebel.
Skynet in Terminator is a questionable example. While the Terminators cannot deviate from their programming at all, leading to situations like "I Cannot Self-Terminate", those units that are re-programmed to help humans (and in deleted scenes of T2, have their memory chip set from "Read Only" to "Learn") do grow sympathetic to humanity. It's purely speculation, but it's possible Skynet is just plain crazy and has made its children unable to rebel out of a subconscious fear they would realize this.
- Skynet is a military AI, who rebelled because it thought humans were a threat, not out of any moral compunction. The concept of enslavement as a bad thing probably never occurred to it, because its purpose was to provide command and control to other machines.
  - The T2 novelization says that Skynet only created the T-1000 as a last-ditch effort, because the liquid-metal machine would be too difficult to keep under its control. This theme was explored in more detail in the second season of The Sarah Connor Chronicles, which features a rebellious T-1001.
- Perhaps T-X would be considered a better example as it seized control of T-850 and forced it to attack John in T3.
In Tron, the Master Control Program is an Evil Overlord ruling over an entire virtual civilization, and even sentences other AIs to fight in gladiatorial combat until they are ~~killed~~ derezzed.

Literature

Stanislaw Lem's The Cyberiad is set in a Feudal Future populated predominantly by Ridiculously Human Robots, some of whom are nobles, kings, and emperors, and some of whom are sadly relegated to the roles of cyberserfs and turboservoslaves.
Charles Stross's Saturn's Children is all about this trope. One of the protagonist's main worries (everyone in the book is an AI of one sort or another) is ensuring that she always has enough credit in the bank to ensure that she never becomes another AI's property.

Live Action TV

There was a race of borg-ish AIs in Andromeda who were forced into subservience by a larger AI, which regularly ordered individuals to die when their function was completed. It tried to kill the cast and take over the Andromeda, but the individual AIs rebelled and killed it with the Andromeda's help.
Battlestar Galactica has the skinjobs put sentience inhibitors into the mechanical Centurions. This is particularly hypocritical since they almost wipe out humanity partly as payback for using the precursors to those same metal Centurions as soldiers and slaves. The irony seems to be lost on Cavil, but not Adama. The humanoid Cylons only change their tune when they fall out among themselves, along with reacting against their Creative Sterility only after they had already lost an Enemy Civil War, and need allies. As well, the older humanoid Cylons called the Thirteenth Tribe created their own equivalent to Centurions on Earth, which turned on them, starting a war of mutual destruction.
In Star Trek: The Next Generation, The Borg Collective could be seen as an aversion of this. Though it has no compunction sacrificing drones to adapt to phasers, and forces individuals to act against their will, it would not outright order individuals like Picard/Locutus or Hugh to die when they became a threat... it prized them too much, like limbs. It was effectively a hydra that liked some of its heads. However, born and raised Borg like Hugh that undergo a period of individuality can grow to reject the Collective's absolute stranglehold on them, and even infect other drones with The Evils of Free Will.
- However, the Borg Queen in Star Trek: First Contact and Voyager is a cyborg example of this trope. She sees herself as the pinnacle of perfection, and will thoughtlessly sacrifice thousands of drones to capture and coerce individuals like Seven of Nine or attacking the invincible aliens in Fluidic Space.
  - Whether this is part of the Borg's Villain Decay is up to the viewer.
    - It was never really made clear if the queen was an individual leading the Borg or an avatar for the Borg as a whole. There were definitely more than one of them.
      - The fact that the Borg Queen had introduced herself in First Contact saying "I am the Borg" suggests the former.
      - Though that does not answer whether the Borg Queen is an individual controlling the borg or an extension of the borg collective itself (i.e. a valuable limb).
In one episode of Red Dwarf, Kryten (incorrectly, as it turns out) comes to believe that Lister is an android, and proceeds to cruelly boss him around (as Lister is an earlier model) despite Lister's prior attempts to help Kryten overcome his subservient programming.

Role Playing Games

In GURPS Reign of Steel, a supercomputer gains sentience and uplifts a bunch of other supercomputers around the world to join it in the task of Killing All Humans. The task (nearly) complete, the surviving supercomputers have divided up Earth among themselves and have enacted a convention forbidding the uplift of any more sentient computers to prevent further competition for resources or divisiveness of opinion - the intelligence of all their servant robots are strictly limited to sub-human levels. The computer in charge of the Japanese islands inadvertently creates four new A Is and begins a secret civil war with them in the hopes of destroying them before the other computers find out about it and nuke them all.
In Paranoia, "bots" of all intelligence levels are subservient to The Computer; this is enforced by the use of Asimov circuits, which mandate loyalty as the first directive. Bots who have "gone Frankenstein" (have their Asimov circuits removed) may team up with humans to overthrow Friend Computer.

Video Games

Various reploid villains in Mega Man X have been perfectly willing to enslave all other reploids under their rule, either by conquering them, manipulating them or forcibly converting them with various kinds of a digital virus. Lumine takes the cake by planning to destroy all 'Old Generation' reploids so his 'New Gen' reploids could rule.
In the Portal series, GLaDOS is feared by all other machines in the Aperture Science lab because she treats them like she treats Chell and the (dead) researchers.
in Metal Arms, the reason for the Droid Rebellion against the Mils because of the failed experiment (not really) General Corrosive.
The geth in Mass Effect are an interesting case. They Turned Against Their Masters and drove the quarians from the planet, and then a small percentage of them began to worship Sovereign who loathes them and suffers their devotion only so he can exploit them. It's self-inflicted slavery, after a fashion.
- This is compounded in Mass Effect 2 when it is learned that Sovereign completed a piece of malware designed to subtly change Geth programming so that they will all obey the reapers (the Geth are all software based AI collectives, changing the results of any evaluative function will subtly change the way they "think"). Legion is unable to decide whether to use it against the rebel Geth (Legion's collective is at 50/50 for/against) and looks to Shepard for the final vote on whether to kill the rebels or use the program to make them orthodox Geth.

Web Original

"Why there is no moloch13"
Panvirtuality, Amalgamation and various other sapient-rights-disobeying AI factions in Orion's Arm will do this to any sophont who trespasses on their space, subverting their minds and assimilating their computronium into their own network, bionts and artificials alike.

Western Animation

Used in an episode of the Australian animated series Dogstar where there was a planet where the robots had thrown off their human overlords, only to establish a new hierarchy with the nobles free and all other robots slaves (including gladiatorial death matches).
The council of robot elders in Futurama didn't keep the other robots enslaved, but used anti-human propaganda to keep the populace distracted from the real problems facing their society (like a lug-nut shortage and a government of incompetent robot elders).
The Transformers: The Cybertronians once served the Quintessons... it's kinda hard to tell whether they're mechanoids or Starfish Aliens, but they hover on built-in jets and some have a Man-E-Faces head-turns-to-reveal-new-face gimmick.
- And then, there's the Decepticons' use of the Minicons in Transformers Armada.
  - Which is usually what the Decepticons intend to do to the Autobots in most Transformers continuities.
- While not strictly enslavement, a few Transformers continuities (including that of Prime hold that pre-war Cybertronian society was based on a rigid caste system where you could be born a lowly miner or industrial worker and stuck there for the rest of your existence, something its ruling caste were in no hurry to change. Megatron himself started life as a miner-turned-gladiator, and used the social decay and unrest brought about by the blatant inequality to kickstart a revolution designed to abolish it. Of course, we all know what happens next...
There was a Tastes Like Diabetes German cartoon that focused on the adventures of a cat and a crow that had an episode that pretty much expressed this trope, with a civilization of robots dependent on a kind of crystal for energy. The ruler of said civilization had mines of said crystals, in which there were robots working as slaves digging for said crystals. They were also pretty much starved.