There is no such character as Yazneg in the Hobbit book. In “The Hobbit: An Unexpected Journey” he is the right-hand orc of Azog the Defiler. Yazneg leads a party of orcs who start trailing Thorin, Gandalf, Bilbo and the dwarves in the wild, not long after they leave Hobbiton. The orcs are under Azog’s orders to ambush and kill them. After tracking them for several days, they finally catch up with them just as they’re leaving the Troll’s cave. Radagast enlists his “Rhosgobel Rabbits” bunny sled to divert the orcs and, thanks to him and the appearance of a hunting party of Elves led by Elrond, the party escapes. Yazneg returns to inform Azog that they got away, that they were attacked by Elves and that he barely escaped with his life. Azog is not amused and, after skewering Yazneg with his iron-forked hand, he feeds Yazneg to his wargs.
Like most of the orcs in the Hobbit movies, Yazneg is a completely CGI character. He is voiced by actor John Rawls who originally also physically played him before the production decision was made to switched the orcs to CGI.
Analysis: The character name, Yazneg, was trademarked by the Saul Zaentz Company in July 2012 related to games, playthings, dolls, etc.. A Lego Yazneg action figure is now available.