Sergei Barsov (or Sergei Borzov in the novelization) is a fictional Soviet agent and Major Anya Amasova's lover. He appears in the 1977 James Bond film The Spy Who Loved Me and its accompanying novelization and was portrayed by Michael Billington.
After making love to his girlfriend, Anya Amasova, Barsov leaves to complete a mission in Austria, which was to kill James Bond. He and his minions tried to kill him on a downhill ski chase in Austria, but James killed him and escaped.
His death was announced to Amasova by General Gogol, to which Amasova voiced her hope to find the man who killed him. When both the Russians and British lose contact with their submarines, the KGB had Amasova partner with Bond to investigate, unaware of Bond's part in Barsov's death. While in Sardinia, Amasova discovers that Bond was in Austria the same day of Barsov's death, and demands to know if he killed him. Although not recognizing him from their sole encounter, James realizes only he could have pulled the trigger and confesses to killing Barsov. A vengeful Anya then swears to kill Bond after their mission is completed.
Sergei was a member of Otdyel II, the operations and executions branch of SMERSH in the film novelization of The Spy Who Loved Me, but was never mentioned as a member in the actual film. Borzov was the romantic love interest of Agent XXX before being killed by James Bond in the opening sequence.