Is Frodo (from Lord of the Rings) a Christ allegory?

Well, you can look at this several ways. For one, Tolkien stated that Lord of the Rings was not a Christian work, and yet there are Christian symbols throughout the book. But I would suggest actually reading the LoTR books and the New Testament to understand this better. To answer your question, yes, in my opinion, Frodo is a Christ allegory. They both carry a huge burden to save the world, the cross and the ring, both know they are risking their lives, and both live.