Lanai (Hawaiian: Lānaʻi, Hawaiian: [laːˈnɐʔi, naːˈnɐʔi], , also US: ,) is the sixth-largest of the Hawaiian Islands and the smallest publicly accessible inhabited island in the chain. It is colloquially known as the Pineapple Island because of its past as an island-wide pineapple plantation. The island's only settlement of note is the small town of Lanai City. As of 2012, the island was 98% owned by Larry Ellison, co-founder and chairman of Oracle Corporation; the remaining 2% is owned by the state of Hawaii or is privately owned homes.

Lanai is a roughly apostrophe-shaped island with a width of 18 miles (29 km) in the longest direction. The land area is 140.5 square miles (364 km²), making it the 43rd largest island in the United States. It is separated from the island of Molokaʻi by the Kalohi Channel to the north, and from Maui by the Auʻau Channel to the east. The United States Census Bureau defines Lanai as Census Tract 316 of Maui County. Its total population rose to 3,367 as of the 2020 United States census, up from 3,193 as of the 2000 census and 3,131 as of the 2010 census. As visible via satellite imagery, many of the island's landmarks are accessible only by dirt roads that require a four-wheel drive vehicle due to the lack of paved roadways.

There is one school, Lanai High and Elementary School, serving the entire island from kindergarten through 12th grade. There is also one hospital, Lanai Community Hospital, with 24 beds, and a community health center providing primary care, dental, behavioral health and selected specialty services in Lanai City. There are no traffic lights on the island.