Helms

"Helms have a common enough purpose: to protect the vulnerable, fleshy parts of the head from skull cracks, and make gouging eyes out a bit harder. Sturdier helms can weigh quite a bit in exchange for providing ample protection."

- Game Guide

Helms are a type of armor in Diablo series. In all three games of Diablo series, Helms are a separate part of characters' gear. They provide both protective and offensive bonuses.

Diablo I
In Diablo I, heavier helms have higher Strength requirements. They have less Defense than Chest Armor, but are the only other piece of protection one may equip.

Diablo II
Helms return in Diablo II. They come in many variations, some classes having gear specifically designed for them: Druid Pelts, Barbarian Helms and Circlets. Helms may have up to three Sockets.

Unlike Diablo I, helms are actually shown on a character model in Diablo II, but Circlets are a way to give heroes a bare-headed look.

Diablo III
In Diablo III, helms offer a major bulk of Armor, and in addition to all-item affixes, may roll resistances, one Socket, Critical Hit chance, increased damage of secondary skills, Life %, Life regeneration, Life per Hit,, health globe / gold pickup range, status effect duration reduction, experience, and chance to Fear on hit. Legendary helms often roll other stats.

Wizard Hats, Voodoo Masks and Spirit Stones are special class-restricted types of helms. They may roll all the same stats, as well as bonuses to characters' class resources and skills.

In Diablo III, helms are a visible piece of equipment, and may be transmogrified or just made 'disappear' with the use of Vanishing Dye. Any helm may be transmogrified into a class-specific helm (Wizard Hat, Voodoo Mask or Spirit Stone), but only by the respective class characters. Class-specific helms may be transmogrified into normal helms without restrictions.

Some helms, when equipped, alter the character's hairstyle, hiding excessive hair from view.