AD 1

AD 1 or AD-1 may refer to:

• Year 1 anno Domini in the Julian calendar
• AD.1 or AD Seaplane Type 1000, a British seaplane of the First World War
• Airship Development AD1, a British non-rigid gas-filled advertising airship, 1929–1931
• Douglas AD-1 Skyraider, an attack aircraft developed in the 1940s
• NASA AD-1, an oblique-wing research aircraft developed in the 1970s
• AD1, a fictional masculinist brotherhood in St Trinian's 2: The Legend of Fritton's Gold
• AD-1 experiment, an antimatter research project