Beast mask

The beast, wolf (lupine) or  (lycan) mask is one of the many forms of head items. But behind stats, such masks are very desirable for their appearance as part of a roleplaying outfit, especially after Cataclysm, which has introduced both the worgen race and the transmogrification feature.

List of masks
There three models of masks.

Beast masks
All of these are mail.
 * Replica Beaststalker's Cap (Darkmoon Faire replica of Beaststalker's Cap, hunter Dungeon Set 1) - BoE, vendor
 * Replica Beastmaster's Cap (Darkmoon Faire replica of Beastmaster's Cap, hunter Dungeon Set 2) - BoE, vendor
 * Far Seer's Helm - BoP, Kurenai vendor
 * Mok'Nathal Beast-Mask - BoP, drop (Auchenai Crypts)

Wolf masks. Model I
The most of these are leather, and exceptions come from a single quest.
 * Embrace of the Lycan - BoP, drop (Zul'Farrak)
 * Wolfshead Helm - BoE, crafted by leatherworkers, usable by s only
 * Spiritcaller's Mask - BoP, There Can Be Only One Response
 * Mask from The Elusive Ironjaw / Welcoming the Wolf Spirit
 * Helm of Lupine Cunning (cloth)
 * Wolf Hunter's Guise (leather)
 * Helm of Lupine Grace (mail)
 * Helm of Lupine Ferocity (plate)

Wolf masks. Model II
All of these are mail.
 * Replica Coif of Elements (Darkmoon Faire replica of Coif of Elements, shaman Dungeon Set 1) - BoE, vendor
 * Replica Coif of The Five Thunders (Darkmoon Faire replica of Coif of The Five Thunders, shaman Dungeon Set 1) - BoE, vendor
 * Big Bad Wolf's Head - BoP, drop (Karazhan)
 * Headdress of the First Shaman - BtA, archaeology find
 * Headdress of Inner Rage - BoE, Outland world drop
 * Mask of the Howling Storm - BoP, drop (Mana-Tombs)
 * Mystical Coif of Elements - BtA, guild vendors

Trivia

 * Beast masks were likely inspired by the Rexxar's mask from Warcraft III. So they are very desirable for s.
 * Wolf masks were likely inspired by the Shaman unit of Warcraft III. So they are very desirable for s.