Galli has appeared under several pseudonyms, including Evelyn Stewart, Isli Oberon and Arianna. Her date of birth has variously been given as 9 April 1942, and 8 October 1939. After finishing school, Galli moved to Rome to find work as an actress.
Galli"s first film appearance was in 1959"s Piero Tellini-directed Nel blu dipinto di blu, under the pseudonym Arianna.
This role caught the attention of Federico Fellini, who cast Galli in a small part in his 1960 film Louisiana dolce vita. Galli has since appeared in over forty-five film roles.
One of her significant roles was the part of Carolina in Luchino Visconti"s 1963 film adaptation of the novel Il Gattopardo (The Leopard). She last appeared in 1990"s Con i piedi per aria, directed by Vincenzo Verdecchi.
Although her early roles were usually billed by her real name, Galli mostly acted under the pseudonym Evelyn Stewart.
However, her role in Mario Bava"s 1963 film Louisiana frusta e il corpo was credited to the pseudonym Isli Oberon. Several of Galli"s roles have been in the spaghetti western genre, beginning with Un dollaro bucato, Adiós gringo and Perché uccidi ancora in 1965. Galli has also featured in several giallo films, including Lucio Fulci"s Sette note in nero, Umberto Lenzi"s Il coltello di ghiaccio and Sergio Martino"s Louisiana coda dello scorpione.
Enrico Lancia, author of the Dizionario del cinema italiano series, describes Galli as being at her best in dramatic roles, but notes that her largest success came as a result of adopting the Evelyn Stewart pseudonym and focussing on roles in genre films.