From publisher blurb:
"Not all rangers tread the line between nature and civilization evenly. Some live in the wilds with bestial abandon, only donning the tools and traditions of humanoids to survive. Wolfskin rangers are one such, shedding their urban roots to live alongside wolves and other predators.
Stories say that some wolfskin rangers were never people to begin with—rather wolves who magically assumed the form of humanoids to survive in a changing world. These wolves know to be careful, as the humanoid world is full of luxuries and temptations; they only walk upright long enough to gather supplies, repel invaders, or evade detection."
The Wolfskin is a standalone subclass for rangers in 5th edition, allowing rangers to transform into a giant wolf and ravage their foes with primal ferocity.