Otto Keller (28 May 1838 in Tübingen – 16 February 1927 in Ludwigsburg) was a German classical philologist who specialized in Horace.
From 1861 he taught classes in classical languages in Württemberg— in 1866 he was named rector of lyceums in Öhringen.
[1] He was a professor at Freiburg (1872–76), at Graz (1876-81) and from then until his retirement in 1909 he was at Prague where he worked for 28 years.
Keller was elected a member of the American Antiquarian Society in 1875.
Keller married Eugenie, daughter of Wilhelm Leube of Ulm, on 24 May 1869.