Blagoi Simeonov Popov (Bulgarian: Благой Симеонов Попов) (22 November 1902 – 28 December 1968) was a Bulgarian Communist activist and Comintern executive who was one of the co-defendants along with Georgi Dimitrov and Vasil Tanev in the Leipzig trial.
After the trial, Popov moved to Moscow in February 1934. He studied there until 1937 when he was caught up in the Stalinist purges. He spent the next seventeen years in a Soviet Gulag until he was officially rehabilitated in 1954.