Louise Viktoria Tolstoy (born Louise Viktoria Kjellberg July 29, 1974 in Sigtuna Municipality, Stockholm County) is a Swedish jazz singer. She is the daughter of Erik Kjellberg, and the great-great-granddaughter of writer Leo Tolstoy. Tolstoy was a housemate in season one of Big Brother in 2000.
She has been married to designer Per Holknekt.