John Call Cook, PhD (April 7, 1918 – October 12, 2012) was an American geophysicist who played a crucial role in establishing the field of ground-penetrating radar and is generally regarded as contributing the fundamental research to develop the field. Cook is also known for demonstrating that aerial surveys can map surface radioactivity to enable much more efficient prospecting for uranium ore, for inventing electrostatic detection of hazardous ice crevasses, and for developing other novel techniques in remote sensing.