No longer just a comic strip for the Yale newspaper, Doonesbury hit the mainstream newspapers. Not exactly an underground comic, but its leftish political content meant that some newspapers put the trip on the editorial page instead of with the rest of the comics.
Fighting white supremacists and fascists in the streets is not new. As Mark Bray points out in his new book titled Antif: An Anti-Fascist Handbook (JBAKC), there was a group in the 1970s and 1980s called the John Brown Anti-Klan Committee that was but one such group who took it to the streets. Another was the Communist Worker's party, who lost five of its members when the Klan shot them down in the streets of Greensboro, NC while undercover FBI informers looked on.
Here is a link to some newsletters from the 1970s. They are archived (along with lots of other material) at the Freedom Archives website. https://search.freedomarchives.org/search.php?view_collection=7&year=1979