Medea Vittoria Irma Norsa (1877–1952) was an Italian papyrologist and philologist.
She headed the Istituto Papirologico from 1935 to 1949.Norsa was born in Trieste in 1877 to Michele and Silvia Krosna.
She studied at a girls' school in Trieste before going to university in Vienna and then Florence, initially to study Italian literature.
In 1906, she earned a degree and began to collaborate with her mentor Girolamo Vitelli on the Papiri Greci e Latini della Società Italiana (PSI); this collaboration continued up to Vitelli's death in 1935 and resulted in 11 volumes of the work.Norsa died in Florence in 1952.