Käthe Kollwitz (July 8, 1867-April 22, 1945) was a German artist who worked in painting, etching, lithography, woodcuts, and sculpture.
Biography on Wikipedia: https://en.wikipedia.org/wiki/K%C3%A4the_Kollwitz

Two Children at the Bannister by Käthe Kollwitz
c.1927, Charcoal on faded drawing cardboard / Käthe Kollwitz Museum, Cologne, Germany

Käthe Kollwitz on Artnet: http://www.artnet.com/artists/k%C3%A4the-kollwitz/

Further reading:
http://blogs.getty.edu/iris/kathe-kollwitz-agent-of-change/
https://www.artic.edu/articles/910/kathe-kollwitz-an-art-of-resistance
https://www.kaethe-kollwitz.berlin/en/