Many of Bruegel's works were not macabre, rather they were quite mundane in their subject matter. A few of his notable works, however, were quite death-oriented, earning him a place on this list.

Wikipedia on Pieter Bruegel the Elder:

Pieter Bruegel the Elder or Brueghel (c.1525 – September 9, 1569) was a Netherlandish Renaissance painter and printmaker known for his landscapes and peasant scenes (Genre Painting). He is nicknamed 'Peasant Brueghel' to distinguish him from other members of the Brueghel dynasty, but is also the one generally meant when the context does not make clear which "Brueghel" is being referred to. From 1559 he dropped the 'h' from his name and started signing his paintings as Bruegel

From Wikipedia on the Triumph of Death:

The painting is a panoramic landscape of death: the sky in the distance is blackened by smoke from burning cities and the sea is littered with shipwrecks. Armies of skeletons advance on the hapless living, who either flee in terror or try vainly to fight back. Skeletons kill people in a variety of ways - slitting throats, hanging, drowning, and even hunting with skeletal dogs. In the foreground, skeletons haul a wagon full of skulls, and ring the bell that signifies the death knell of the world. A fool plays the lute while a skeleton behind him plays along; a starving dog nibbles at the face of a child; a cross sits lonely and impotent in the center of the painting. People flee into a tunnel decorated with crosses whilst a skeleton on horseback slaughters people with a scythe. The painting clearly depicts people of different social backgrounds - from peasants and soldiers to nobles and even a king - being taken by death indiscriminately.