The Angel Moroni plays an important part in Mormon history. He supposedly was a white-skinned inhabitant of ancient America, a Nephite General. He supposedly appeared to Joseph Smith as an angel and showed Smith where he had buried the gold plates which Smith would translate into the Book of Mormon.
Interestingly enough, Moroni appeared to Smith on or about the Autumnal Equinox each year for four years.
Moroni originally was the being who appeared to Smith in the First Version of the First Vision. Later he was left out of that event.
How interesting that a golden idol sits atop the most holy monument in Mormondom!