Iao

Iao may refer to:
 * IAO (album), an album by avant jazz musician John Zorn
 * Iao (Gnosticism), an archon corresponding to Jupiter
 * Iao Theater, a theater in Wailuku, Hawaii
 * Iao Valley, a tourist attraction in Maui, Hawaii
 * Sayak Airport (IATA code: IAO), also known as Siargao Airport, in Surigao del Norte, Philippines
 * ιαω, an early Greek form of the tetragrammaton, or name of God

IAO may stand for:


 * Incorporated Association Of Organists
 * Indian Astronomical Observatory, home of the highest telescope in the world
 * Information Awareness Office, a branch of the U.S. Defense Advanced Research Projects Agency (DARPA)
 * Interests, Activities, and Opinions - IAO or psychographic variables
 * International Accreditation Organization (Houston, TX)
 * International Academy of Osteopathy, an international school offering academic training in osteopathy
 * International Astronomy Olympiad, an astronomy competition for high-school students
 * Interparliamentary Assembly on Orthodoxy, an organization of parliamentarians of the Eastern Orthodox Church
 * Institut d'Asie Orientale (Lyons Institute of East Asian Studies), a centre for research in human and social sciences at Université Lumière-Lyon 2 and Institut d'études politiques de Lyon
 * Institute for Art and Olfaction, a non-profit organization
 * Istituto agronomico per l'oltremare (Overseas Agronomic Institute), a technical and scientific body of the Italian Ministry of Foreign Affairs