Diabolik

Diabolik is a comic book character created in 1962 by sisters, Angela and Luciana Giussani for the Astorina publisher.

Genesis
Diabolik was born when Angela Giussani, observing commuters in the Stazione di Milano Cadorna train station in Milan, imagined a “pocket-size” comic book that could be read while waiting for, or riding on, the train, and that could be easily tucked away in a pocket.

Angela did market research and found out that many commuters’ preferred reading genre was crime/mystery fiction (giallo, in Italian).

According to another version, Angela came up wth Diabolik after finding a Fantomas book on the subway.

Thus, the “pocket-size” (tascabile, in Italian) comic book was born. Many other publications later imitated this format.