H20

H20 (H twenty) may refer to:
 * Highway H20 (Ukraine)
 * HMS H20, a submarine
 * McDonnell XH-20 Little Henry, a type of helicopter
 * Nissan H20, a type of engine
 * Xian H-20, a Chinese stealth bomber
 * Halloween H20: 20 Years Later, a 1998 horror sequel
 * H20, the ICD-10 code for uveitis