What knights wore on their helmets?

There's the Great helm of Albert von Pranckh, 14th century that shows the helmet style often used by knights of the Teutonic Order. There is a link to an image below.

There's also the Codex Manesse depicting Tanhauser in the habit of the Teutonic Order along with a great helm topped with horned wings.

They would've worn horned helmets, or several different variations of the great helms with or without horned or any other types of ornamentation throughout the 13th and 14th century. There's also tournament heraldry of knights with horns, animals, fans depicting heraldry and a whole assortment of items on their great helms in order to distinguish themselves from other knights on tournaments and battlefields.