Crested helm

A common form of elven helmet was the crested Helm, worn by the Feanorian Warriors and also by Sindarin Warriors.The crested elven hem is basically a tall helmet with nose and cheek guards and a huge crest of feathers (eagles or seagulls).

speculations
The crested elven helms as described by Tolkien were perhaps inspired by historical helmets as the roman helms, illyrian helms but most likely the greek hoplite helmet.