It looks like we have details on the newest Wildling member joining the ranks for the fifth season of Game of Thrones. Zachary Baharov will be taking on the role of Loboda, according to his agency CV.
According to Watchers on the Wall, Loboda is the leader of a cannibalistic Wildling tribe. Now this could be taken that he will be the new leader of the Thenns, but I think it might be something else. Simply going off of the above picture, Loboda does not have the same scarring that the other Thenn characters had in season 4. So maybe Loboda will be the leader of another cannibalistic Wildling tribe, or he actually is the new leader of the Thenn's, but is just missing the scars.
SLIGHT SPOILERS AHEAD
As for his role in the upcoming season we don't have to much information. All we know about Loboda's role in the upcoming season is that he will have a scene with leading cast members where they discuss battle plans.
Now which leading characters will be involved, and what battle they are planning, is completely unknown so far. But I'm sure you can speculate all on your own. For my thoughts on all of this, keep an eye out for my season 5 predictions post coming later in the week!