Karin Smirnov or Smirnoff, née Strindberg (26 February 1880 – 10 May 1973) was a Finland-Swedish writer. She was the daughter of August Strindberg and Siri von Essen.
Karin Smirnov was a socialist; she married Russian Bolshevik Vladimir Smirnov and lived with him in the Soviet Union. She wrote plays and also books about her mother and father, and their marriage.