"He?" by Guy de Maupassant

Published in 1883.

The picture used is by Georges Lemoine, or possibly by William Julian-Damazy, I can't quite figure out what's up with it. Regardless, it's actually an illustration for "The Horla", but it fits well enough for this story as well.

To follow along: https://www.gutenberg.org/files/21327/21327-h/21327-h.htm#Page_152