Shigeo Shingo consulted for Toyota, teaching seminars for Taiichi Ohno among other things. Was a leader in developing and publicizing the Toyota Production System (the roots of lean maufacturing, lean thinking and Just in Time - JIT). He was a consultant to Toyota, which was quite rare. In general Toyota did not use consultants.
Very interesting interview with Isao Kato on Shingo's influence on Toyota.
He is credited with developing the concept of Poka-Yoke (mistake-proofing).
He lived from 1909 to 1990.Books