I2

i2, I-2, I 2 or I2 may refer to:
 * I2, a statistical measure of study heterogeneity used in meta-analysis
 * I2, a military acronym for an image intensifier
 * I2, the chemical formula for molecular iodine
 * I2 engine, a designation for a straight-twin engine
 * i2 Group, a visual investigative analysis software company
 * i2 Technologies, an international supply chain management firm
 * Haplogroup I2 (Y-DNA), the human Y-chromosomal haplogroup
 * LB&SCR I2 class, a 1907 British class of 4-4-2 steam tank locomotive
 * Grigorovich I-2, a biplane fighter aircraft of the Soviet Union
 * Internet2, a not-for-profit US computer networking consortium
 * Interstate 2, a highway in the US state of Texas
 * Göta Life Guards (infantry) (1816–1939), a Swedish Army infantry regiment
 * Värmland Regiment (1939–1973), a Swedish Army infantry regiment
 * I2, a rank-into-rank axiom in mathematical set theory
 * Incredibles 2, a 2018 American animated superhero film by Pixar
 * Iberia Express, a Spanish low-cost airline (IATA code: I2)
 * JSUB I-2, a Type J1 submarine of the Imperial Japanese Navy
 * I2, the logo for Industrial Illusions, a fictional corporation in Yu-Gi-Oh!