Guglielmo Achille Cavellini (1914–1990), also known as GAC, was an Italian artist and art collector. He began his career in the 1940s and 1950s as a painter and then turned his attention to the collecting of Italian abstract art. Resuming his work as an artist in the 1960s, Cavellini created a broad range of work from Neo-Dada to performance art to mail art, of which he became one of its prime contributors with his Exhibitions at Home and Round Trip works. In 1971 Cavellini introduced the concept autostoricizzazione (self-historicization), through which he sought to create a deliberate popular history surrounding his life through self-promotion. He designed exhibitions and home catalogs, posters, pins, stickers, memorabilia, stamps, performances, happenings all in planning for the 2014 official celebration of the centenary of his birth.