Underwood Dudley (born January 6, 1937) is a mathematician formerly of Depauw University who has written a number of research works and textbooks, but is best known for his popular writing. Most notable are several books describing crank mathematics - people who think they have squared the circle or done other impossible things. This sort of work is thrown away by most mathematicians, but Dudley has saved and analyzed it, calling it the folklore of mathematics.
These books, which alternate between enjoyment of and exasperation with such cranks, include The Trisectors (ISBN 0883855143), Mathematical Cranks (ISBN 0883855070), and Numerology: Or, What Pythagoras Wrought (ISBN 0883855240). They helped him win the Trevor Evans Award for expository writing from the Mathematical Association of America in 1996.