It comes from a free Overwatch trial ad in China - fitting, because all these skins are tied to the classic Chinese epic Journey to the West. Specifically,
Zenyatta seems to be Tang Sanzang - the Buddhism master of Monkey King Sun Wukong. Worth noting, another name for Tang Sazang is Tripitaka - who you may remember was represented in Ninja Theory's Enslaved: Odyssey to the West as a super-hot post-apocalyptic techno-hippie chick.
Winston is, naturally, Sun Wukong, the Monkey King.
Roadhog is Zhu Bajie, a pig monster and apprentice of Tang Sanzang, and Rein is Sha Wujing, another apprentice of Tang Sazang.
This is all very cool, of course, but all of these heroes have already received new legendary skins. Zenyatta has his Nutcracker Christmas skin, Winston got the (awesome) Yeti skin, Roadhog got Junkenstein's Monster (Halloween) and Rein got two legendaries when the Eichenwald map launched.
Heroes without a new legendary skin so far..? McCree, Hanzo, Sombra, Ana, Soldier, Pharah, Bastion, Widow and Sym. Wonder what - if anything - is comin' down the pike for them? That being said, the above, along with the Mei and D.Va skins that Blizz have shown off, are pretty damned groovy.
Year of the rooster!