who wrote the fog

The title “The Fog” most commonly refers to a 1975 horror novel written by James Herbert.

Because your question is very short, note that:

• If you meant the horror novel “The Fog,” the author is James Herbert.

• If you meant the 1980 horror film “The Fog,” it was directed and co‑written by John Carpenter, with Debra Hill as co‑writer.

So, for “who wrote The Fog?” as a book question, the answer is James Herbert.