| Birth Name: | Leonard Emerson Opdycke |
| Birth Date: | 22 May 1929 |
| Alma Mater: | University of Rochester |
| Death Place: | Poughkeepsie, New York |
Leonard E. Opydycke (May 22, 1929 – February 23, 2023) was an American historian, editor, and author, who specialized in pre-WWII aviation history.
Leonard Emerson Opdycke was born in Boston, Massasscusetts in 1929. His education included earning an undergraduate degree in English, in 1951 from Harvard College, and in 1965 a Master's degree in Psycholinguistics from the University of Rochester.
He is best known for being the founding editor of two magazines dealing with early aviation;
In 1999, Opdycke's book French Aeroplanes Before the Great War was published. This was the result of more than 15 years of research, initially with Michel Bénichou, editor of , but then as an individual endeavor.