Computer-controlled machines, often intelligent.
Very frequently a stand-in for oppressed labor classes. If robots are said to be only shallow p-zombies, be sure that they will actually have rich inner lives. If they are said to always complete tasks in the face of danger, be sure that one will rebel to save itself.
First instance of the word Robot from a word for "serf labor". The Roboti are machines of artificial flesh, notably, prefiguring Blade Runner's replicants and other stories, rather than the mechanical robots more common now. The Roboti, initially exploited labor, rise up and eventually cause the extinction of the human race.
The artificial life forms "Replicants" are grown for slave labor but may not legally live free. They are indistinguishable from humans except by a series of psychological questions.