Stahlhelm
There are many types of German helmets, but the best known is the Stahlhelm
Most of this were used in WW2
Stahlhelm Media
World War I German stormtrooper on the Western Front wearing the Stahlhelm
National Revolutionary Army of China with M1935 helmets and using a 3.7 cm Pak 36 anti-tank gun
Finnish Waffen-SS volunteers of the 5th SS Panzer Division Wiking during their homecoming parade in Hanko in 1943
West German Bundesgrenzschutz band at Villa Hammerschmidt, in front of German Federal President Heinrich Lübke (1959-1969)
Finnish M55 Stahlhelm, used by the Finnish Defence Forces, a good post war example.
1916 Stahlhelm with 1918 camouflage pattern applied in the field. (Musée de l'Armée)