Ida Helmi Tuulikki Pietilä (18 February 1917 – 23 February 2009) was an American-born Finnish graphic artist and professor, born in Seattle, Washington, United States.
Pietilä was one of the most influential people in Finnish graphic arts, and her work has been shown in numerous art exhibitions.
She worked as a teacher in the Academy of Fine Arts, Helsinki, for many years, and later trained graphic artists and wrote instructional books about graphic arts.
Pietilä began her studies at Turku Drawing School (now TUAS Arts Academy of Turku University of Applied Sciences), which she attended from 1933 to 1936, and went on to study at the drawing school of the Finnish Art Association (1936–1940), the University College of Arts, Crafts and Design in Stockholm (1945–1949) and the Fernand Léger Art Academy in Paris (1949–1953).
During her studies, she met her future life partner Tove Jansson; they collaborated on many works and projects, including the Moomin works, in collaboration with Pentti Eistola.
These are now exhibited at the Moomin Museum in Tampere.
Jansson's and Pietilä's travels and summers spent together on the Klovharu island in Pellinki have been captured on several hours of film, shot by Pietilä.
Several documentaries have been made of this footage, the latest being Haru, yksinäinen saari (Haru, the lonely island) (1998) and Tove ja Tooti Euroopassa (Tove and Tooti in Europe) (2004).
The first exhibition of Pietilä's work was in Turku in 1935.
Her first private exhibition was in 1951.
She has participated in the Purnu group's summer exhibitions since 1967, with a retrospective exhibition in 1986.
She has also participated in several exhibitions abroad.
Pietilä has gained praise for her work; she was awarded the Pro Finlandia medal in 1963 and the title of professor in 1982.Pietilä inspired the energetic figure Tooticky in Jansson's Moomin books.
The architect Reima Pietilä was Tuulikki Pietilä's brother.Pietilä died at her home on 23 February 2009.