Theodor Karl Ernst Adolf Liebknecht (19 April 1870 – 6 January 1948) was a German socialist politician and activist.

Born in Leipzig in 1870 as the son of Wilhelm Liebknecht and the brother of Karl Liebknecht, Theodor Liebknecht studied law and worked, together with his brother Karl and Oskar Cohn,[1] as a lawyer in Berlin from 1899 on, becoming politically active after his brother's murder in January 1919.

A right-wing member of the SAPD, he was opposed to the introduction of Leninist schemes of organization into the party.

Following the Nazi rise to power, he emigrated to Basel, Switzerland in 1933 and was later employed by the International Institute of Social History in Amsterdam from 1936 to 1939.

Liebknecht died in Altendorf [de], Brome, Germany, in 1948.