Promethea, by Alan Moore. "You can’t really “get” comics until you’ve read something by Alan Moore. He’s not always the most feminist-friendly writer in the world, but his work does amazing things with the medium. Promethea gets overly preachy (and if you ask me, kinda boring) in its later books, but its beginning is a great depiction of a strong female character and a unique representation of shared female power. Also, it’s worth reading just for JH Williams’ amazing art."
Alan #Moore - Saga of the Swamp Thing Vol. 1 - The issues collected here were groundbreaking not just for Moore but for comics as a whole. Swamp Thing was reportedly the first series that abandoned the Comics Code and composed solely for adults, and Moore’s issues created characters like John Constantine and crossover successes like Hellblazer and The Sandman.