"Envoy Extraordinary" is a 1956 novella by British writer William Golding, first published by Eyre & Spottiswoode as one third of the collection Sometime, Never, alongside "Consider Her Ways" by John Wyndham and "Boy in Darkness" by Mervyn Peake.

The story concerns an inventor who anachronistically brings the steam engine to ancient Rome, along with three of the Four Great Inventions of China (gunpowder, the compass, and the printing press).

[3] Golding later adapted "Envoy Extraordinary" into a play called The Brass Butterfly, first performed in Oxford in 1958 starring Alistair Sim and George Cole.

On the day of Amphitrite's demonstration voyage, Mamillius and Phanocles are nearly killed and the ship's engine, called Talos, is sabotaged, destroying several of the returning Posthumus's warships and most of the harbour through fire.

Over steam-cooked trout, the Emperor tells Phanocles that he has decided to marry Euphrosyne himself to avoid embarrassing Mamillius, as he has deduced that the reason she never takes off her veil is that she has a hare lip.

After its first night at the Strand on 17 April 1958, critics made much of a number of boos mixed in with the applause, calling the play "slack" and "lukewarm", though the Sim's performance did receive praise.

[10] Walter Sullivan writing for The Sewanee Review in 1963, described The Brass Butterfly as "witty but by no means profound" and "Envoy Extraordinary" as "a not very successful novella about ancient Rome".