Born in San Giuliano Milanese, Ernesto Grassani attended the Scuola d'Arte Applicata del Castello in Milan and the Ars Pubblicita, where he specialized in animation. He subsequently worked in various graphic studios, as well as the ateliers of Kara and Tenenti. In 1972, he began a longtime assiciation with fellow artist Giuseppe Montanari. Together, they worked on a large amount of comics series, including 'Igor' for Edifumetto, 'Storie Nere' for Ediperiodici, 'Roaring Trio' for LancioStory, 'Le Streghe' for Corrier Boy and 'Sharon Shade' in Full. He eventually joined Daim Press/Bonelli, where he continued his collaboration with Montanari on series like 'Il Piccolo Ranger', 'Mister No' and 'Dylan Dog'.