Who Goes There?

A classic story written by John W. Campbell under his Don A. Stuart pseudonym and published in the August 1938 Astounding.

Scientists working in Antarctica discover a crashed alien spaceship. In the course of investigating it, they accidentally revive one of the crew by thawing it and — in due course — discover that it is made of some protean substance which can consume and duplicate human beings. Which of them have already been taken over? The tension is substantial, and humanity only triumphs by hard work and last-minute good fortune.

It was made into a movie three times.