Bilbo Baggins is 111 years old when he gives his famous birthday party in J.R.R. Tolkien’s The Lord of the Rings.
The celebration takes place in Hobbiton at the beginning of The Fellowship of the Ring. Bilbo’s unusually long life is presented as one of the effects of possessing the One Ring, which he found during his journey in The Hobbit. His birthday is shared with Frodo, although Frodo is much younger.
Bilbo uses the party as the setting for his disappearance. During his farewell speech, he puts on the Ring and vanishes, leaving the startled guests behind. He then leaves the Shire and gives the Ring to Frodo, beginning the central chain of events in the trilogy.
The number is sometimes confused with Frodo’s age. Frodo is 33 when he comes of age, and he is 50 when he leaves the Shire with the Ring. Bilbo’s 111th birthday is therefore a key date for both characters.