E1, E01, E.I or E-1 may refer to:
Transportation Aircraft Azcárate E-1, a Mexican sesquiplane trainer Fokker E.I, a German fighter aircraft Grumman E-1 Tracer, an American airborne early warning aircraft Hydra Technologies E1 Gavilán, a hand-launched Mexican unmanned electronic surveillance drone Junkers E.I, the Idflieg designation for the 1916 Junkers J1 monoplane LVG E.I, a 1915 German two-seat monoplane NFW E.I, a 1917 German monoplane fighter Pfalz E.I, a Morane-Saulnier H monoplane built under licence for Germany Siemens-Schuckert E.I, a 1915 German single seat monoplane Standard E-1, a 1917 early American Army fighter aircraft
Automobiles BMW E1, a 1991 and 1993 German electric/hybrid city car concept BYD e1, a 2019–present Chinese electric city car Dongfeng Fengguang E1, a 2019–present Chinese electric mini crossover Haima E1, a 2020–present Chinese electric city car Roewe E1, a 2012 Chinese electric city car concept later produced as the Roewe E50 E1, a Mazda E type piston engine Switch E1, a bus Built by Switch Mobility Bestune E01, a compact electric crossover
Submarines HMS E1, an E-class submarine of the Royal Navy USS E-1 (SS-24), a 1917 E-class submarine of the United States Navy
Roads European route E1, from Northern Ireland to Spain E1 European long distance path, a long-distance hiking route from Norway to Italy London Buses route E1, a transport for London contracted bus route Tomei Expressway and Meishin Expressway, route E1 in Japan North–South Expressway Northern Route and New Klang Valley Expressway, route E1 in Malaysia E1 expressway (Philippines) (North Luzon Expressway, Subic–Clark–Tarlac Expressway, and Tarlac–Pangasinan–La Union Expressway), expressway route in the Philippines E1 expressway (Pakistan) E01, Southern Expressway in Sri Lanka
Trains and locomotives E1 Series Shinkansen, a Japanese high-speed train Bavarian E I, a German steam engines locomotive model Ceylon Government Railway E1, a steam locomotive EMC E1, a diesel locomotive LB&SCR E1 class, an 1874 British 0-6-0 steam locomotive NCC Class E1, a Northern Counties Committee Irish steam locomotive NER Class E1, an 1898 class of small 0-6-0T steam locomotive PRR E1, an American PRR 4-4-2 steam locomotive SP&S Class E-1, a 1934 steam locomotives class
Science and mathematics Biochemistry E1 (HCV), a viral structural protein found in hepatitis C E1, a unimolecular elimination mechanism in organic chemistry E1-enzymes, also known as Ubiquitin-activating enzymes, an enzyme which catalyzes the first step in the ubiquitination reaction, which targets a protein for degradation via a proteasome] E1 regulatory sequence for the insulin gene Estrone, a hormone Pyruvate dehydrogenase (E1), the first component enzyme of pyruvate dehydrogenase complex Acireductone synthase, an enzyme Haplogroup E1 (Y-DNA), a human Y-chromosome DNA haplogroup
Mathematics Exponential integral, , mathematical function the E1 series (number series) of preferred numbers
Medicine E1-isoprostane, a type of isoprostane
Businesses and organizations E1 Music, an independent record label in the United States E1 Corp., a Korean chemical and oil company, member of the LS Group Entertainment One, an international media company
Electronics Honda E1, a predecessor of the ASIMO humanoid robot Olympus E-1, a digital single-lens reflex camera
Places E1 (West Bank), an area east of Jerusalem in the West Bank E1 postcode district, London, England, United Kingdom
Other uses E01, ECO code for the closed variation of the Catalan Opening in chess E01, the Encase Image File Format E-1 (rank), the pay grade for enlisted ranks of Private, Airman Basic, and Seaman Recruit in the United States Military E1 grade, a difficulty level in rock climbing E-1 (rocket engine), a liquid propellant rocket engine E1 carrier, an E-carrier European telecommunications standard E1, an AMD CPU from the Bobcat (microarchitecture) family E1, abbreviation for the Oracle JD Edwards EnterpriseOne software E1 on Gardiner's sign list, representing the bull E1 Series (boat racing), an international powerboat racing series
See also List of highways numbered 1 1E (disambiguation)