Theodor Becker (23 June 1840 in Plön – 30 June 1928 in Liegnitz) was a German civil engineer and entomologist primarily known for his work with flies.
He worked with Paul Stein, Mario Bezzi, and Kálmán Kertész on Katalog der Paläarktischen dipteren published in Budapest from 1903.
Becker’s collection is in the Humboldt Museum, Berlin.