The Flakpanzer IV "Ostwind" (East Wind in English) was a German self-propelled anti-aircraft gun based on the Panzer IV tank.

It was developed in 1944 as a successor to the earlier Flakpanzer IV/2 cm Vierling Wirbelwind.

In addition to its intended role as an anti-aircraft weapon, the fast-firing gun was highly effective against light vehicles and minor fortifications.

A closed-top design would have been preferable, but this was not possible due to the heavy smoke generated by the gun.

The Ostwind's main improvement over the Wirbelwind was the FlaK 43's increased range and stopping power over the 2 cm Flakvierling 38 and slightly better armor on its turret, albeit it had a lower fire rate.