In this video about Janet Sobel's painting Milky Way, it's noted that she was a pioneer of the paint dripping technique that directly inspired Jackson Pollock. Sobel was a Ukrainian artist who lived from 1893 to 1968 and didn't begin her painting career until she was 45 years old.
Although the term "drip painting" may be used to describe work like Sobel's, her technique is clearly much more complex than simply dripping paint on a canvas. If you look closely at any one of her artworks you'll find deeply intricate patterns and abstractions. I had no idea who Sobel was until today, or that her awesome paintings were a precursor to Pollock's.