I am a quote-unquote "liberal" and I'm pretty nice. One of the reasons you don't have people testifying and speaking on the record is some who did that were prosecuted and jailed during Obama's 2 terms.
The general word you might be looking for is "radical". It means changing things from the root, so to be against the status quo to a large magnitude. Not perfect since it could also apply to a person of the right-wing who wants to change things, but through U.S. history it is usually meant for Leftist. The fringe minority who wear masks and attack people or cause damage are sometimes referred to by police as "Black Bloc." There are still plenty of the tye-dye mellow ones still with us