W18

W18 may refer to:


 * W-18 (drug), a designer drug
 * British NVC community W18, a woodland community in the British National Vegetation Classification system
 * Hansa-Brandenburg W.18, a German flying boat fighter
 * HMS St Aubin (W18), a tug of the Royal Navy
 * Malgana language
 * Mercedes-Benz W18, an automobile
 * Snub dodecahedron
 * Suburban Airport, in Anne Arundel County, Maryland, United States
 * W18 engine, an eighteen-cylinder engine
 * Water-jugs-in-stand (hieroglyph), an Egyptian hieroglyph