I didn’t care for the movies much. I noticed that all evil beings were initially good. As I know little about Catholicism can someone tell me - Just who was Tom Bombadil?
A totally fictional character, invented by J.R.R. Tolkien. There is no one-to-one matchup of LOTR characters or events with Catholicism.
One can see in the figure of Tom Bombadil echoes of Christian souls such as St. Francis of Assisi, whose experience of God had a directness and simplicity outside societal norms and intellectual structures. See G.K. Chesterton's biography.
On the other hand, Tolkien had many other historic and literary influences other than the Catholic Faith. Someone with more knowledge of the subject than I might find a source for the character within the English and Scandinavian historical and mythological traditions in which Tolkien specialized.