Grünenwaldt, born in 1910 in Hamme-Mille in the town of Beauvechain, in Walloon Brabant, Belgium, and died in Mouscron on March 23, 2008, is an Art Brut artist.
Martha Grünenwaldt spent her childhood playing the violin to accompany her father, a traveling musician, and hardly ever attended school. Married at twenty-three to a musician, she worked in a factory until the birth of her daughter. After four years of marriage, she leaves home with her child and leads a wandering life, playing the violin on cafe terraces. But in 1940, her husband took back custody of their daughter. Martha Grünenwaldt finds a job as a servant in a castle, where she is forbidden to touch her instrument. In 1968, his daughter offered to move in with her.