William Crosby Marshall (September 21, 1870 – February 1, 1934) was an American mechanical and consulting engineer, Professor of Machine Design and Descriptive Geometry at the Sheffield Scientific School of Yale University and author.

The next two years at Yale he was assistant in mechanical engineering and from 1894 to 1902 instructor in drawing and descriptive geometry.

[2] In those years Marshall had continued his graduate study at the Sheffield Scientific School since 1895, and obtained his C.E.

[4] In 1917 Marshall had started as mechanical engineer with the Holt Manufacturing Company in Peoria, Illinois, when on September 13, 1917, he was called upon to serve in the war industry.

First he was Captain in Ordnance Department, U.S.A, and became assistant chief of the Inspection Division of the Small Arms Weapons Section at Washington, D.C. At the end of the war he was discharge February 19, 1919.