Judith Beheading Holofernes
This is one of my favourite paintings.
It's a Renaissance oil on canvas by Artemisia Gentileschi.
She has depicted a scene from the Old Testament, in which the Israelite leader Judith and her assistant Abra have drugged an enemy warlord, and are engaged in cutting his head off.
I love the calm expressions on the women's faces, although I'm told that overzealous restoration has smoothed furrows of concentration and intense effort from their brows.
Compare this with a painting on the same subject by Michelangelo Merisi da Caravaggio. A much more sanitised view of a murder.