W9

W9 may refer to:

• Wizz Air UK (IATA code: W9)
• Air Bagan (former IATA code: W9), a former airline of Myanmar
• London Buses route W9, England

• Form W-9, used by the US federal government for tax purposes
• W9, a postcode district in the W postcode area, England
• W9 (TV channel), a French television channel
• W9 (nuclear warhead), an American nuclear artillery shell
• Japanese minesweeper W-9, several ships
• Niland Geyser (scientific designation), California, US

• 9W (disambiguation)