Bavarian B IIIs were steam locomotives of the Royal Bavarian State Railways (Königlich Bayerische Staatsbahn).
Eight examples were delivered by Maffei in 1852; the remainder came from Hartmann.
The machines by Hartmann had great similarity to those of the Class A IV, which were manufactured at the same time.
Unlike the Hartmann engines, these locomotives also had a steam dome.
All the engines had a Crampton boiler with smooth tubes and a Kirchweger condenser.