Nosy Be (Malagasy pronunciation: [nusʲ be]; formerly Nossi-bé and Nosse Be, lit. 'big island') is a volcanic island off the northwest coast of Madagascar. Nosy Be is Madagascar's largest and busiest tourist destination. It has an area of 320.02 km² (123.56 sq mi), and its population was 109,465 according to the provisional results of the 2018 Census.

Nosy Be means "big island" in the Malagasy language. The island was called Assada by the French during the early 17th century. Nosy Be has been given several nicknames over the centuries, including "Nosy Manitra" (the scented island).