I posted here a little while back. I'm not a "Typewriter Guy," but I developed an interest in collecting duplicates of the typewriters used by the horror greats.

H.P. Lovecraft used the same typewriter his entire career, a Remington Standard No. 6. He bought it in 1906. There's some confusion as to whether he bought it used or new, a friend referred to it as "A refurbished 1906," but most people think he bought it new. Anyway, you can't let yourself think like that, so 1906 is the target year. Most people think that even if he bought it used, the typewriter itself was a 1906. Here's an article:

https://tentaclii.wordpress.com/2011/07/05/lovecrafts-typewriter/

After years of trying, I've managed to purchase a Remington Standard No. 6, with a serial number of 155580 that dates to 1906!!! Is it Lovecraft's typewriter? Well, chances are huge that it's not, but it COULD be.

If Lovecraft sent it in in 1935 to be refurbished, as claimed, and if he sent it to the Remington Co., there might be a serial number recorded.
Barring that, if a photocopy of one of Lovecraft's authenticated manuscripts (one he typed himself) could be obtained, forensic testing could identify a particular machine.

Robert E. Howard (Conan's creator) used an Underwood #5 (It's in a private collection, but there's controversy. It was always believed that Howard's typewriter was an 1926, but the one that's claimed to be his dates to 1928. Is his typewriter still out there??!! Howard also used the same machine his entire career.

Robert Bloch wrote Psycho, and many other of his greats on an Olympia SG1. It's in a private collection.