Giuseppe Paolo Stanislao "Beppo" Occhialini ForMemRS[1] (Italian pronunciation: [dʒuˈzɛppe okkjaˈliːni]; 5 December 1907 – 30 December 1993) was an Italian physicist who contributed to the discovery of the pion or pi-meson decay in 1947 with César Lattes and Cecil Frank Powell, the latter winning the Nobel Prize in Physics for this work.

In 1932, he collaborated in the discovery of the positron in cosmic rays at the Cavendish Laboratory of Cambridge, under the leadership of Patrick Blackett, using cloud chambers.

In 1944 he returned to England, working at the Wills Physics Laboratory in Bristol, where he studied cosmic rays.

In 1947, while in Bristol, he contributed to the discovery of the pion or pi-meson decay in collaboration with César Lattes, Cecil Frank Powell and Hugh Muirhead.

During WW II, staying in Brazil, then a country hostile to Italy, he became an authorized alpine guide in the Parque Nacional do Itatiaia, where there is a peak named "Pico Occhialini".