Quick answers

What is The King in Yellow about?

An important early classic of fantasy/sci-fi. [Main story:] The ill effects of a soul-destroying play, to read which brings doom. A discovery that changes living flesh to stone. The mad adherents of a cult of evil powers from beyond. A lost traveler is suddenly 400 years in the past. Great writing; powerful emotions. Chambers wrote mainly conventional stuff, but not here.

When was The King in Yellow published?

The King in Yellow was published in 1895.

Who made The King in Yellow?

The King in Yellow was written by Robert W. Chambers.