| William P. MacKinnon | |
| Birth Date: | 9 September 1939[1] |
| Nationality: | American |
| Known For: | Independent historian |
| Education: | Mount Hermon School[2] |
| Alma Mater: | Yale Harvard (MBA, 1962)[3] |
| Occupation: | Management consultant and former General Motors executive |
| Spouse: | Patricia |
| Website: | Occasional guest author - Keepapitchinin.org |
| Awards: | 2008 Mormon History Association Thomas L. Kane Award Utah State Historical Society Dale L. Morgan and LeRoy S. Axland awards[4] |
William P. MacKinnon, an American independent historian. A management consultant, MacKinnon is a historian of the American West, Mormon history, and Utah history[5] who was described by Richard E. Turley in 2018 as "the acknowledged expert"[6] and by Thomas G. Alexander in 2019 as "the most knowledgable authority"[7] on what was known in its time as the American War of the Mormons' Succession (or more recently "the Utah War"), a topic of which MacKinnon began his study as a Yale sophomore history major in 1958.[8] In 2018, MacKinnon presented the 35th Juanita Brooks Lecture at Dixie State University: "Across the Desert in 1858: Thomas L. Kane’s Mediating Mission and the Mormon Women who Made it Possible."[9], MacKinnon lived in Santa Barbara with his wife, Patricia.[10]
MacKinnon has published over thirty journal articles on the history of the American West. In 2010, he contributed an article to .