Who - or what - is the Happy Mask Salesman? It is one of the Zelda series' most prolific mysteries. First appearing as just another run of the mill shopkeeper in Hyrule's Castle Town Market, the Happy Mask Salesman is revealed in Majora's Mask to be a world traveling purveyor of ancient magical relics and the only known individual other than Skull Kid to know of the link between Hyrule and Termina in the Lost Woods and he possesses the means to cross that interdimensional border between the two worlds freely. Fancy that! A humble shopkeeper! He possesses extensive knowledge of Termina given his acquisition of Majora's Mask via unknown means and an understanding of its nature and origin. So it would stand to reason that he has spent a great deal of time in Termina to be so well acquainted with its lands and history and culture. He also apparently possesses magical powers and there is even some evidence to suggest that he may be omniscient, given that Termina's three day time loop doesn't seem to affect him. He is also prone to sudden and physically aggressive mood swings that stand in stark contrast to his usually calm placid demeanor, which is none-the-less creepy and unsettling. Is this guy even human? There could be a link between the Salesman and one of Ocarina of Time's most enigmatic locals. The haunted ruins of the Lost Wood's Forest Temple. Just what is this place? A haunted old manor built deep within a perilous wood that warps space time so hard it hides an interdimensional portal to a parallel world and most creatures other than supernatural monsters can't navigate it without getting hopelessly lost and turning into something horrible. Who in Hyrule would build a castle in an impossible place? Who in Hyrule even could build a castle anywhere at all given that by any indication only the Royal Family of Hyrule appears to be wealthy enough to build a castle on such a scale. The other races certainly didn't build it. But the place was clearly inhabited at one point and there is strong indication to suggest that it was a home of some sort given the furnishings, decor and the nature of the grounds. During the events of Ocarina of Time, however, the place is in ruins and haunted - principally by uniquely named sister poes who in all likelihood were once residents of the estate. But what does the forest temple have to do with the Happy Mask Salesman? Well, it could be that he was a former resident of the manor. The Salesman is the only known figure not from the forest who is capable of navigating the Lost Woods. So that would make him the only known person other than Saria and eventually Link who is capable of finding the Forest Temple. Furthermore, the interdimensional border between Hyrule and Termina is also in the Lost Woods. This demonstrates that HMS doesn't just have the ability to navigate the Woods safely but also possesses a familiarity with its environs. The origins of the Forest Temple remain unknown as do whatever circumstances lead to its ruined and haunted state. But if there's weird unexplainable stuff going on in Hyrule, it's easy to blame the Sheikah - the Royal Family of Hyrule's mystic ninja servants and secret enforcers. The Sheikah are responsible for the communications network of magical Sheikah Stones scattered across Hyrule and are known for their research into magical melodies (the Sun's Song) and their use of magical artifacts like the Lens of Truth. The Sheikah are also associated with one other of Hyrule's temples: the Shadow Temple, which is commonly believed to have been a clandestine torture and murder dungeon operated by the Sheikah in service to the Royal Family. Could the Forest Temple have served a similar purpose? Could the Forest Temple have been a Sheikah fortress? Perhaps it was the secret headquarters of the Sheikah? It would have served such a purpose well, given the nature of the Lost Woods to confound travelers and turn them into undead stalfos. The Forest Temple would have been well hidden. And if the Sheikah possessed a means by which to safely navigate the Woods like the Lens of Truth is capable of navigating the Haunted Wasteland, it would have been the perfect hideout for this secret caste of shadow ninjas. The Happy Mask Salesman could be a Sheikah. Like the Sheikah, the Salesman has a knowledge of and predisposition towards magical artifacts. Indeed, hunting them is a personal past time of his at the very least perhaps even his life's work. He appears to possess innate magical abilities as Sheikah are known for. He can even teach songs for the Ocarina, an ability he shares with known Sheikah Impa which she presumably passes on to trained Sheikah "Sheik" and also exhibited by Sheikah brothers Sharp and Flat (who are also, incidentally, uniquely named Poes, we'll get to that later...) Few other figures are capable of knowing or directly teaching songs for the Ocarina of Time, a magical heirloom of the Royal Family of whom the Sheikah are associated but whom the Salesman has no apparent connection to. And if the Sheikah are capable of navigating the Lost Woods, then this is another ability the Salesman has in common with them. Furthermore, in the spirit of a clandestine ninja, the HMS first appears as a nondescript shopkeeper living and working amidst the general Hylian population of Castle Town, but yet no one seems to be aware of his unique abilities and extraordinary ventures. He hides his true nature in plain sight... like some sort of ninja or something! My theory is that the Forest Temple is another Sheikah facility and the Happy Mask Salesman is a Sheikah who was a former resident or occupant of the manor or who was associated with it enough to have spent some time there. At some point possibly during the Hylian Civil War, something happened to cause the manor to become abandoned and haunted. It is possible that some sort of magical ritual went awry or the manor was somehow infiltrated or attacked and the Sheikah abandoned it. I suspect that the Poe sisters who haunt the Forest Temple and who confront Link during his time there were Sheikah in life who died when the castle fell or who were otherwise left behind when it was abandoned. The only other named poe ghosts in the game are Sheikah brothers Sharp and Flat, all of whom demonstrate a degree of sentience that other generic poe ghosts show no indication of which may be due to their Sheikah heritage. It could also be that the HMS has no affiliation with the Sheikah, but that he was a prior inhabitant or resident of the manor. Perhaps a family of powerful magicians. Given the evidence of demon activity in the Forest Temple to account for the haunting, it could be that the manor fell to demons, perhaps as a result of a tragic event or the Lost Wood's influence on the place, and somehow whoever the HMS was at the time became influenced by or possessed by demons which would account for his supernatural abilities. Such an event would have taken the lives of the Poe Sisters, leaving him (or whatever's left of him) as the sole survivor. Demonic possession would also explain the HMS's creepy demeanor and sudden fits of rage.