Otto Karl Albrecht Ritschl (26 June 1860, Bonn – 28 September 1944, Bonn) was a German theologian, the son of Albrecht Ritschl.
After studying at Göttingen, Bonn and Giessen, he became professor at Kiel (extraordinarius) in 1889 and afterwards at Bonn (extraordinarius 1894; ordinarius 1897). He published, among other works, Schleiermachers Stellung zum Christentum in semen Reden über die Religion (1888), and a Life of his father (20 vols, 1829-96).