Throughout the 1960s and 70s, London-based Big O Posters helped define the new and democratic art medium of the psychedelic poster, a vehicle for rebellion against the old order that went hand in hand with the music, literature, and film of the time. This is a comprehensive collection of works published by Big O artists, astonishingly creative folks whose artistry developed almost completely outside the influence of the art establishment. Included in more than 300 images are works by 19 artists, including Martin Sharp, Roger Dean, H.R. Giger, Robert Venosa, and Vali Myers, whose signature styles include sci-fi, fantasy, visionary, botanical, and surrealism. In addition to hundreds of original works, this book digs below the surface to offer insights and anecdotes about the era, the artistic process, and reveals connections to artists from the past Aubrey Beardsley, Alphonse Mucha, Kay Nielsen whose spirit chimed with the age of Big O Posters.