IGY may refer to:

• Immunoglobulin Y (IgY), a type of antibody found in birds but not mammals
• International Geophysical Year (I. G. Y.)
• "I.G.Y. (What a Beautiful World)", a 1982 song by Donald Fagen
• Israel Gay Youth
• Ingenuity (helicopter) (ICAO operator code: IGY), NASA defunct solar-powered autonomous drone helicopter on Mars

• All pages with titles beginning with IGY
• All pages with titles containing IGY
• Iggy (disambiguation)
• IGI (disambiguation)
• IG (disambiguation)
• GY (disambiguation), for 1 Gy
• GM LGY engine