What's the earliest example in Science Fiction of a robot 100% mimicking a human?

Question

The classic example is, of course, Stephen Byerley from Asimov's "Evidence".

Were there SciFi works featuring robots that are able to be indistinguishable from humans (by sight or behavior) prior to that? (September 1946).

What's the earliest such example?

Answer 1

“Able to be indistinguishable” is highly debatable here^*, it's not actually science fiction^† and the word “robot” does not turn up in this text^‡. But if we allow this work at all, then it may well be the earliest appearance: Oʟɪᴍᴘɪᴀ from E.T.A. Hoffmann's 1816 short story Der Sandmann.

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*_{The protagonist is in fact unable to distinguish her from a human, but it's pretty clear that his senses aren't quite alright. At least the adaption Oʟʏᴍᴘɪᴀ in Jacques Offenbach's Les contes d'Hoffmann is more of a creepy if beautiful puppet (including a crank mechanism that needs to be regularly used to re-power her mechanical clockwork), that only a drugged madman could possibly mistake for a human.}

^†_{I would perhaps call it steampunk fantasy today.}

^‡_{She's called an Automat.}

Answer 2

The original robots in R.U.R. by Karel Čapek (published in 1920) were very human-like in appearance (they were made of protoplasm, not of metal). Their likeness to humans isn't a central plot point like in “Evidence”, but it is mentioned (“Sulla isn't a person, Miss Glory, she's a robot.”).

Answer 3

One of the earliest Sci-Fi movies with that theme is Fritz Lang's Metropolis, wherein one of the main characters is duplicated in appearance using a robot. Dates to 1927. In this one, the robot is in fact made to look exactly like the human character.

Wikipedia: Metropolis (film)

Answer 4

Lester Del Rey's "Helen O'Loy" (1938) beats out Evidence by a few years.