This one's a bit of a deep cut, but if you played Warcraft III's expansion The Frozen Throne and did the Founding of Durotar campaign, Samuro was an Orc Blademaster who aided Rexxar in his fight to protect the fledgling orcish nation.
While Grom Hellscream was also a Blademaster, Samuro really instilled the class with a distinctly samurai-like feel, including the banner worn on the back and the katana-like sword. Samuro was a member of the Burning Blade Clan, which, as we learned in Warlords of Draenor, was originally considered a very honorable clan that was focused on discipline and precision, but would later fall to demonic corruption. Samuro represented one of the last remnants of the original Blademaster tradition.
I'll confess I'm not sure that Heroes of the Storm desperately needs another Orc character (so far we've got four, not counting Samuro, and we don't have any Trolls or Draenei, and the only Gnome is actually a dragon while the only Tauren is sort of a joke character.)
It looks like Samuro will have some of the traditional Blademaster abilities. Mirror Image, Critical Strike, and Windwalk are your Q, W, and E abilities, while your heroics are Bladestorm and Illusion Master, the latter of which allows you to swap places with one of your Mirror Images.
Samuro will be a melee assassin, and hopefully the voice acting won't be a kind of offensive Japanese accent this time!