Katrin Siska (born December 10, 1983 in Tallinn, Estonia) is an Estonian singer and member of the Estonian girlpower pop-rock-group Vanilla Ninja. Siska was born to a Russian mother Leena and an Estonian father Toomas. She has a younger sister Triin-Ketlin. She was a member of a choir while in school and started playing the piano when she was 7 years old.