The type of story I'm curious about is one where a God or Goddess is so enamoured with the human experience, that they willingly give up their divinity to mingle among humanity and live+die as they do. (Not out of wanting to save humanity, but of a desire to participate in it, so Jesus does not count.)
Any mythology or religion is fine, and I'm willing to hear about other stories that don't exactly fit this bill.
In recent history/mythology, there is the 人間宣言 Ningen-sengen, where the Japanese Emperor Hiro-Hito, who according to Shinto was a living god until the end of WW2. In this proclamation, the Emperor gave up his divine ancestry claims.
In Christianity, there are stories unsupported by the mainstream doctrines of angels who give up their divine state to become and experience humanity. They are generally categorized as fallen angels, although in mainstream Christianity this term means angels who chose to follow Lucifer.
