The 503rd Heavy Panzer Battalion (abbreviated s.Pz.Abt. 503) was a German heavy Panzer Abteilung (a battalion-sized unit) equipped with Tiger I tanks and Panzer IIIs. In 1944, it was re-equipped with the new Tiger II. The 503rd saw action on the Eastern and Western Fronts during the Second World War. As with other German Heavy Panzer Detachments, it was normally not assigned to a single corp, but shuffled around according to war circumstances.