Guglielmo Achille Cavellini (1914-1990), also known as GAC, was an Italian artist and art collector. Beginning his career as a painter in the 1940s and 1950s, Cavellini then became a major collector of contemporary Italian abstract art. In the 1960s Cavellini resumed his activity as an artist creating  a broad range of works from Neo-Dada to performance art to mail art, and out of which he became known for his Exhibitions at Home and the Round Trip works. In 1971 Cavellini coined the term autostoricizzazione (self-historicization), upon which he created a deliberate popular history through self-promotion believing it to be his task to write his biography before it could be written after his death which he determined would happen in 2014.