USS Helena was a Brooklyn-class light cruiser built for the United States Navy in the late 1930s, the ninth and final member of the class. The Brooklyns were the first modern light cruisers built by the US Navy under the limitations of the London Naval Treaty, and they were intended to counter the Japanese Mogami class; as such, they carried a battery of fifteen 6-inch (150 mm) guns, the same gun armament carried by the Mogamis. Helena and her sister St. Louis were built to a slightly modified design with a unit system of machinery and an improved anti-aircraft battery. Completed in 1939, Helena spent the first two years of her career in peacetime training that accelerated as tensions between the United States and Japan increased through 1941. She was torpedoed at the attack on Pearl Harbor in December 1941 and was repaired and modernized in early 1942.

The Brooklyn-class cruiser was a class of nine light cruisers built for the United States Navy between 1935 and 1938. Armed with five triple 6-inch (152 mm) gun turrets, they mounted more main battery guns than any other standard US cruiser. The Brooklyn-class ships were all commissioned between 1937 and 1939, in the time between the start of the Second Sino-Japanese War and before the invasion of Poland. They served extensively in both the Pacific and Atlantic theaters during World War II.