Italian submarine Alagi was an Italian Adua-class submarine serving in the Regia Marina during World War II. She was named after the Amba Alagi mountain in Ethiopia. Alagi was built in the CRDA shipyard, in Monfalcone. She was laid down on 19 March 1936, launched 15 November of the same year, and commissioned on 6 March 1937. On 8 June 1942, Alagi torpedoed and sank the Italian destroyer Antoniotto Usodimare in a friendly fire incident.