Wells, H. G.
The Invisible Man (1897)
This masterpiece of science fiction is the fascinating story of Griffin, a scientist who theorises that if a person's refractive index is changed to exactly that of air and his body does not absorb or reflect light, then he will be invisible. He successfully carries out this procedure on himself, but cannot become visible again, becoming mentally unstable as a result.
Wells' novel was originally serialised in Pearson's Magazine in 1897, and published as a novel the same year.