H20
H20 (H twenty) may refer to:

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

See also
H2O (disambiguation)