B1 class or Class B1 may refer to:
B1-class Melbourne tram Barry Railway Class B1, 0-6-2T steam locomotives Finnish Steam Locomotive Class B1, 0-4-2ST steam locomotives LB&SCR B1 class, 0-4-2 steam locomotives LCDR B1 class, 0-6-0 steam locomotives LNER Class B1 (disambiguation) LNER Thompson Class B1, 4-6-0 steam locomotives NER Class B1, 0-6-2 steam locomotives Pennsylvania Railroad class B1, electric locomotives