Luckwearer

Even before he found the Ring, Bilbo was already associated with luck (indeed, part of the reason he was chosen to accompany the Dwarves on their Quest was to be the lucky number, so that their party did not have thirteen members). He showed extraordinary luck throughout his adventures, not least in stumbling across the Ring itself while wandering dark passageways beneath the Misty Mountains. Indeed, it is strongly hinted that there was more than luck at work here, and that Bilbo's great good fortune was influenced by greater and more mysterious forces, though Bilbo simply thought of himself as 'lucky'.

Throughout the adventures that followed its finding, Bilbo's possession of the Ring helped his companions numerous times, and so he would naturally come to see himself as the 'Luckwearer'. It was only long afterward that the true power of his Magic Ring was revealed, and it was seen to be not quite so 'lucky' after all, but instead a source of deadly danger.