Agathe Backer Grøndahl (December 1, 1847–June 4, 1907) was a Norwegian pianist and composer.

She was born in Holmestrand, Norway, and later moved with her family to Oslo, where she studied under Otto Winther-Hjelm , Halfdan Kjerulf and Ludvig Mathias Lindeman . Later she studied under Hans von Bülow in Florence, and under Franz Liszt in Weimar.

Grøndahl composed in total 70 pieces, and was a prominent character in Norwegian music life. She was also a close friend to Edvard Grieg. Later in life she became almost completely deaf, forcing her to give up her career as a performing artist.

Agathe Backer Grøndahl died in Oslo, 59 years old.