Even though I disagreed with his prognostications of capitalism's imminent collapse, and his later apologetics for Israel involved some huge mental contortions, Robert Kurz's work -- in particular Der Kollaps der Modernisierung and the Schwarzbuch Kapitalismus -- inspired me to a renewed engagement with Marx's critique of political economy. Kurz was one of the most eloquent polemicists against this pathological, barbaric mode of production.
I just got news of his passing through Ingo Stützle's Twitter feed, and I think Ingo put it best: "I wish he had survived capitalism rather than the other way around."