Caer Ibormeith

In Irish mythology, Caer Ibormeith was the daughter of Prince Ethal Anbuail of Sid Uamuin in Connacht. In Óengus’s dream, which lasted over a year, Caer Ibormeith stood beside his bed. However, when he reached out for her, she would disappear. Every alternate Samhain she would turn to human form for one day, which begins at sunset, and after that, she would revert into being a swan, in which form she would remain for a year before becoming human again the following Samhain.