Eugen Diederichs (June 22, 1867 - September 10, 1930) was a German publisher from Löbitz.
Diederichs started his publishing company in Florence, Italy, in 1896. He moved on to Leipzig, where he published the early works of Herman Hesse, and from there to Jena in 1904. He started publishing the magazine Die Tat in 1912. He married the writer Lulu von Strauß und Torney in 1916.
Since 1988 Diederichs has become an imprint of the Hugendubel publishing house.