Tyr
Tyr was amongst the most honourable of the Gods, even if he did retray his friend; Fenrir.
When Odin wanted Fenrir and his siblings to come to Asgard, Tyr was one of those who escorted them. Fenrir was just a puppy, and the two of them formed a bond that grew as Fenrir did. When Odin wanted Fenrir bound, Tyr fought against this at the start; but an order from the Alfather was not to be disobeyed, and so he put his hand into Fenrir's mouth as promised, tricking his friend into trusting him when he shouldn't so that Gleipnir could bind him. But honour dictated he take the punishment for this deception; and so he lost his hand.
During Ragnarok, Tyr is killed by Garm, Hel's guardian wolf who rivals Fenrir for sheer might and size. Some speculate that Tyr thought it was Fenrir, and sought to make amends with his friend. As a result, the wolf was able to kill him, the mistaken identity being Tyr's downfall.
