According to most dictionaries, an android is an automaton built to resemble a human being. The term could thus be applied to a wide array of constructs seen in both fiction and reality, from any mindless robot that resembles us at the superficial level, to a perfect replica(nt) with practically indistinguishable features.
A prime cinematic example of the latter is Bishop from the movie Aliens, James Cameron's 1986 sequel to the Ridley Scott scifi-horror classic. For the most part, Bishop looks and acts just like any other member of the crew--not counting that fancy knife trick, of course.
Though androids are a staple of science fiction, we might be able to trace the roots of this trope much further back. Mythologies, religious texts, and prehistoric literature around the world have stories that feature artificial humans, built by way of mechanical or sometimes magical means, from the Golem of Jewish folklore to the "iron man" Talus of The Fairie Queene. The Iliad portrays the god of mechanical arts, Hephaestus, as being assisted in his work by animated statues. They are described as "living young damsels, filled with minds and wisdoms" despite being made completely out of gold.
Meanwhile, folklore in Finland speaks of Seppo Ilmarinen, an immortal blacksmith capable of forging nearly anything. In some tales, he's even said to have built the dome of the sky. Alas, despite his prowess as the Eternal Hammerer, he has trouble finding Ms. Right. In one story, stricken with grief over the death of his first wife, Ilmarinen attempts to craft a woman out of gold and silver. He is successful, but finds his new wife too cold to hold.
The correct answer may be one of the earliest works in the science fiction genre, Mary Shelley's Frankenstein. Frankenstein's monster may also have been the first android to show a Pinocchio-like desire for genuine humanity in spite of his artificial origins (in fact, before Pinocchio himself), a trait exhibited in many later characters, like Data in Star Trek: The Next Generation.
I've yet to create any androids of my own, though some of my stories have dealt with a pesky A.I. or two, including the one I'm working on right now. It's very possible my inner scifi nerd will one day lead me down a path that ends in androids, and I'm fine with that. While that path is certainly well-trodden enough to be considered cliche at this point, I still can't get enough of them.
And clearly, I'm not the only one. Human beings have been enchanted by the idea of artificial people since the dawn of the written word, and we haven't stopped building them in our fiction. The most recent example in popular fiction is Ridley Scott's Prometheus. While met with mixed reviews, even those with largely negative opinions of the film are heaping praise on Michael Fassbender's performance as David, the eponymous vessel's android crew member. While most point to this as an example of Fassbender's talent as an actor, I think it also proves that our fascination with this kind of character isn't going anywhere. At least not until the real androids are walking the streets.
Do Androids Dream of Electric Sheep? by Philip K. Dick
The Bicentennial Man by Isaac Asimov
Home Is the Hangman by Roger Zelazny
The Journeyman Project