GI or Gi may refer to:

• G.I., a nickname for U.S. Army soldiers

• GI (album), an album by the Germs
• Gi (Captain Planet character)
• Game Informer, a magazine
• Gert's Inferno, a comic book series
• Global Icon (band), a South Korean group
• Genshin Impact, an action role-playing gacha game developed by miHoYo

• Goethe-Institut, a German cultural association
• General Instrument, an electronics company
• Gesellschaft für Informatik, a German computer society
• Guaranteed Irish, a business membership network

• GI, a complexity class in the graph isomorphism problem
• Galvanized iron

• G_i alpha subunit, a protein
• Gastrointestinal tract (GI tract)
• Gigantocellular reticular nucleus, a subregion of the medullary reticular formation
• Glycemic index, measuring a food's effect on blood glucose

• .gi, the country code top-level domain for Gibraltar
• Gi (prefix symbol) (gibi), a binary prefix
• Global illumination, a group of 3D graphics algorithms

• Guduvancheri railway station (Indian Railways station code), a railway station in Tamil Nadu, India
• Itek Air (IATA airline designator), a former airline based in Kyrgyzstan

• GI, the ISO 3166-1 country code for Gibraltar
• G.I. Generation, a demographic cohort
• Graphics Interface, a conference on computer graphics and human–computer interaction
• Geographical indication, on products which corresponds to a geographical location or origin
• Gi (kana), a syllabic character in Japanese script
• Gi (cuneiform), a sign in cuneiform writing
• Greg Inglis (born 1987), Australian rugby league footballer
• Keikogi, a Japanese martial arts uniform known in English simply as a gi

• G.I. Joe (disambiguation)