The art of adaptation is just that; an art. Adapting a short story, a novel, or even a novella takes a finely honed sense of what worked in the adapted material, of what drew readers and, presumably, a movie studio to purchase the film rights, and what works on the big or small screen. Of the three, the novel is generally the most difficult to adapt, the short story second hardest (because so many details and backstory have to be created from scratch), and that makes the novella, with its limited page count and linear story, usually minus subplots, perfect or near-perfect for the big - or small - screen jump.
John W. Campbell's 1938 science-fiction/horror novella, 'Who Goes There?,' has been adapted twice for the big screen, first, loosely, as 'The Thing from Another World,' produced and ghost-directed by Howard Hawks ('Rio Bravo,' 'Red River,' 'The Big Sleep,' 'His Girl Friday') in 1951 and thirty-one years later, by John Carpenter ('Prince of Darkness,' 'They Live,' 'Halloween') as 'The Thing.' Carpenter's adaptation hews closely to Campbell's novella, with some key differences (which we'll discuss below) while Hawks' adaptation shares a general premise and ideas, but little else with the source material.
[Note: Spoiler alert is in full effect.]