William Thomas Astbury FRS (also Bill Astbury; 25 February 1898, Longton – 4 June 1961, Leeds) was an English physicist and molecular biologist who made pioneering X-ray diffraction studies of biological molecules. His work on keratin provided the foundation for Linus Pauling's discovery of the alpha helix. He also studied the structure for DNA in 1937 and made the first step in the elucidation of its structure.