Google Antifa. They're the Communist component to the alt-right neo-nazis. I don't think either are supported by large groups of people. They're both very fringe. However, they show up n the same places and cause mayhem and friction. They compliment each other pretty well.  The Antifa cause both left and right demonstrations to go bust. Because they smashed some windows in Seattle in 99' at the WTO protest, the police decided to crack down on everyone.