Who Goes There? is a 1938 science fiction novella written by John W. Campbell, Jr. under a pen name. It is available to be read online. This story is the inspiration for The Thing From Another World (1951), The Thing (1982) and The Thing (2011).
SF Signal has a review that says,
It successfully relays the closed-in feeling of the Antarctic camp, the dwindling hope as the situation progresses from unknown to hopeless, and the futility of trying to escape.SFF World says, "over seventy years on, it is still creepy." Horrorphilia says, "I would recommend this novella to sci fi movie and book fans so they can appreciate how influential this story is for themselves."
The photo of John W. Campbell, Jr., at the top of the post, comes from Classic-SF.com.