If by “antihero” you understand the “villain” in the story, I would not agree.
Thorin tried to reconquer the kingdom that was his by birth right though not just for himself but for his kin as well.
But perhaps you may try to start your analysis on the person of Thorin from another angle. “The
Hobbit“ was originally written as a book for children (you have undoubtedly noticed the quite different style of storytelling when comparing to LotR, particularly in the first two thirds of the book). Therefore, if it is a book for children, there is a moral message to it. What could children learn from Thorin’s destiny?
Just as examples (no claim to have noticed all) I personally would retrieve from his ending:
- Even mighty and wise people are prone to weaknesses and sins. If they repent then much is made good (like Thorin apologizing to Bilbo in his last moments) and he will nonetheless be remembered for the good he’s done (like Bilbo grieving over his death).
- Excessive pride and stubbornness without thought for other people’s reflexions or opinions lead to isolation and needless problems (like Thorin behaving towards Thranduil and all of them being locked up).
There is a very strong moral sentence we should all remember which he spoke on his deathbed (gosh, I do like that one!):
“If more of us valued food and cheer and song above hoarded gold, it would be a merrier world.”
If you can join me from that angle of perception, then what would you think about his message in this story?