| August Mencken Jr. | |
| Birth Date: | 18 February 1889 |
| Known For: | Civil engineer, author |
| Notable Works: | The Railroad Passenger Car; An Illustrated History of the First Hundred Years |
| Father: | August Mencken Sr. |
| Relatives: | Henry Louis Mencken (brother) |
August Mencken (February 18, 1889 - May 19, 1967) was an American civil engineer and author. He was the younger brother of Henry Louis Mencken and the son of cigar magnate August Mencken Sr.