Jean Giraud is a cartoonist who is capable of daring metamorphosis and of mastering seemingly irreconcilable universes and narrative techniques. In 1963, with the nom de plume ‘Gir’, he creates a western series, Blueberry, which soon becomes a classic. It is a series that renovates some conventions of its genre, based on a realistic very neat and detailed graphic style. In the same year, Giraud also begins a parallel career with the pseudonym ‘Moebius’, inspired by the famous strip of August Ferdinand Möbius, a German mathematician and astronomer. With the latter pseudonym, he will sign some experimental and avant-garde science-fiction works that will reshape the comics world. By means of examining the complex relationship established by the author with his two pseudonyms, we can shed light not only on his poetics, but also on some developments in the history of comics literature; between the 60s and the 70s, the comic book undergoes a revolution transforming it into a «mature medium capable of expressing itself at every cultural level, from the more coarse to the most refined» (Barbieri 2009, Breve storia della letteratura a fumetti, transl. by the Author).