In no particular order...
Woody Guthrie, Pete Seeger, Phil Ochs, The Black Panthers (Heuy Netwon etc, not the so-called New BPs), the Civil Rights Movement, Malcolm X, Eugene V Debs and the early Socilaist Party, James P Cannon and the early Socialist Workers Party, The Industrial Workers of the World, Joe Hill, Paul Robeson, David Rovics, Counterpunch, Democracy Now, Flashpoints, Pacifica Radio in general, Hunter S Thompson, Interpol (the band), the Abolitionists, The Revolutionary War, The Civil War (the results of), Blues, Folk, Soul, Hip Hop, Free Speech, Trial by Jury, the Native American struggle, the Womens' Lib movement, the LGBT Lib movement, the Anti-War movement (past and present), Tom Paine (ok he was Brit, but Common Sense was the intellectual force behind the Revolutionary War), the Abraham Lincoln Brigade (Spanish Civil War), the GIs who fought fascism in the 40s... but most of all I love the millions of United Statesians and immigrants who are still fighting for a better future for humanity, locally, nationally and globally.
And Ralph Nader and Bernie Sanders are ok too.