E300 or E-300 may refer to: Alexander Dennis Enviro300, a popular British bus built upon various chassis Brandner E-300, an Egyptian turbojet engine HB-E300 series, a Japanese hybrid diesel train type Olympus E-300, a digital camera manufactured by Olympus PowerPC e300, a family of microprocessor cores Ascorbic acid, a compound numbered E300 in the European food additive E number system Eurostar e300, a class of Eurostar passenger trains also known as British Rail Class 373 and TGV TMST Extra 300, an acrobatic monoplane