Iron Tiger is an unlockable character within Call of Duty: WWIINazi Zombies, he can be unlocked by completing a full challenge set in Beneath the Ice the third and last chapter of The Tortured Path, in this case being the "Archaeological Dig" challenge set.
No Handouts. - Escaped without resupply (None for me, thanks.)
Escape without picking up supply drops.
Careful Researcher - Return from an archaeological dig without scrape (Precautionary Explorer)