Ernest Lee Jahncke (October 13, 1877 – November 16, 1960) was United States Assistant Secretary of the Navy from 1929 to 1933.

He was removed in July 1936 for his outspoken opposition to holding the 1936 Summer Olympics in Nazi Germany.

Jahncke served as a delegate at the 1932 Republican National Convention, which re-nominated President Hoover, and as an alternate to the 1936 Republican National Convention, which nominated Alfred M. Landon.

In a 25 November 1935 letter to IOC president Henri de Baillet-Latour, Jahncke wrote: "Neither Americans nor the representatives of other countries can take part in the Games in Nazi Germany without at least acquiescing in the contempt of the Nazis for fair play and their sordid exploitation of the Games.

"[2] In July 1936, Jahncke was expelled from the IOC for his outspoken opposition to holding the Olympics in Germany.