Class 90 may refer to:
British Rail Class 90 German Class 90 tank locomotives with a 0-6-2T wheel arrangement operated by the Deutsche Reichsbahn and its successor administrations, comprising: Class 90.0-2: Prussian T 9, LBE T 9, PKP Class TKi1 Class 90.3: ČSD Class 312.7 Class 90.10: BBÖ 30 (2-6-2T) Class 90.11: JDŽ Class 51 (2-6-2T) Class 90.64: various locomotives taken over in 1949 by the Deutsche Reichsbahn (GDR) Class 90.70: EWA IIIb New South Wales 90 class locomotive, diesel-electric locomotives