The Warrior of Light is a playable Heroes from Dissidia: Final Fantasy, he wears a distinct helmet that has a couple of very long horns pointing upwards.
Life-size Paladin Judgement Helmet paper model from World of Warcraft, created by Drummerthing.
Another one for the cosplayers, life-size Iron Man Helmet papercraft created by our new friend / paper artist Edgar Medrano (aka ScannerJoe).
ScannerJoe in action with a full-on Iron Man armor during the premiere of the Iron Man 2 movie.
Say hello and welcome to Melissa (Lizz) van den Hoogen of Winged Crafts blog, her first paper model is up and it's a life-size Dragonstalker Helmet from World of Warcraft. 
Very nice paper models of the Roman Army's Imperial Helmets, one is for the Centurions (officers) and the other for Legionaries (private soldier). Papercraft designed by Hans-Dieter Richter / Bastelbogen Online.
Life-size version of the Helmet that is part of the Horde Tier 9 Plate Armor set, includes Warrior, Death Knight, and Paladin skin.
A zunari-type kabuto papercraft (head-shaped samurai helmet) by the Honda Museum in Ishikawa Prefecture, Japan.
From the Star Trek Voyager video game, that helmet that is part of the Hazard Team's environmental suit.
The horned helmet of Final Fantasy V and Dissidia's ultimate villain, Exdeath (aka X-Death, aka ExDeath).
I couldn't find much info. on this one except that is was from a show? called Cross Power Warrior Buchi Liger ^^, and this is the mask / helmet of the hero.
The nefarious horned-helmet worn by Judge Magister Gabranth (aka Noah fon Ronsenburg) from Final Fantasy XII.
This year marks the 50th anniversary of the American Footbal League, DIL from IRP has created these football
helmet papercrafts that have the old designs of the AFL teams.