Theodore H. Okiishi (born 1939) is an American mechanical engineer. He is an emeritus faculty member at Iowa State University (ISU), where he also received his bachelors and doctoral degrees. He has written numerous technical papers, and is a co-author of the books A Brief Introduction to Fluid Mechanics and Fundamentals of Fluid Mechanics. The latter has been called one of the "top 10 standard handbooks for mechanical engineers."[1]