Italian cartoonist, Sergio Toppi, often gets referenced as a source of inspiration by artists all over the world.
After starting out in animation and advertising he began doing comics in the 60's. Toppi's works appeared on a host of titles in Italy and abroad: an incomplete list could include Linus, Corto Maltese, Sgt. Kirk and Il Giornalino in Italy. His strips were collected in several books.
He is currently working with the French publisher Mosquito, with which he has made 22 books since 1994.
A nice collection of his work on flickr
Toppi at Editions Mosquito