According to J.R.R. Tolkien’s books, Bilbo and Frodo Baggins share a birthday on 22 September.
Bilbo Baggins was born on 22 September 2890 of the Third Age, while Frodo was born on 22 September 2968. The date is especially memorable because Bilbo celebrates his eleventy-first birthday at the beginning of The Lord of the Rings, when he gives a famously elaborate speech before leaving the Shire.
Frodo’s thirty-third birthday occurs on the same date, making the shared birthday an important link between the two hobbits. Bilbo’s birthday party also provides the setting in which he passes the One Ring to Frodo.
The date is sometimes confused with the publication date of The Hobbit, which was 21 September 1937. It is also a fictional calendar date, so it should not be treated as Tolkien’s own birthday; Tolkien was born on 3 January 1892.