Celebrated American painter Cy Twombly, whose paintings featured scribbles, graffiti and unusual materials and who invigorated American post-War art alongside Jasper Johns and Robert Rauschenberg, has died. He was 83.

From signs and billboard advertisements that loomed high above Times Square to canvases filled with images from popular culture that helped shape the world of art from the early 1960s, James Rosenquist has been painting on a large scale for…