Ellen Thesleff (5 October 1869 - 12 January 1954) was an expressionist Finnish painter, regarded as one of the leading Finnish modernist painters.
Thesleff was born in Helsinki, the eldest daughter of five siblings and her father was an amateur painter.
She took private lessons and then, in 1887, studied for two years at the Finnish Art Society Drawing School (now known as the Finnish Academy of Fine Arts) with Gunnar Berndtson.