The WAGR Fso class were freight steam locomotives operated by the Western Australian Government Railways (WAGR).

The Fso class was a designation assigned to regular Fs class (superheated F class) 4-8-0 locomotives to identify them from the Fsl class which had larger cylinders. Like the Esl and Eso classes, these sorts of classifications were abandoned by the 1940s, with both the Fso and Fsl classes being folded into the normal Fs class.