Zeniff (/ˈziː.nɪf/) is a minor but pivotal person in the Book of Mormon. He is a Nephite. He left Zarahemla with a group of Nephites to go to the land of Nephi. This is remarkable since the Nephites had previously abandoned the land of Nephi. At the time of Zeniff's journey to the land of Nephi, it was inhabited by the Nephite's arch-enemies, the Lamanites. Zeniff became the king of the group of Nephites with whom he went to the land of Nephi.
He is the first of three kings whose story is recounted in The Record of Zeniff. The record concerns a group of Nephites who returned for a time to the land of Nephi but who were ultimately driven out by the Lamanites.
The Record of Zeniff contains a synopsis of the history of the Nephites up to the time of Zeniff. At the time of Zeniff, the Nephites were living in the land of Zarahemla and the land of Nephi was occupied by the Lamanites.
After Mosiah's death, during the reign of his son, King Benjamin, an army of Nephites determined to return to the land of Nephi and "possess the land of their inheritance" (Omni 1:27). Zeniff was among this group. When they drew near to the land of Nephi, Zeniff was sent to spy on the Lamanites, so that their army could destroy them. After seeing the Lamanites, Zeniff felt that they should not be destroyed but that the Nephites should enter into a treaty with them. The (unnamed) leader of the Nephite army, "an austere and blood-thirsty man", viewed this report as treasonous and tried to have Zeniff put to death. Fighting broke out among the Nephites, "the greater part of their army was destroyed", and "those that were spared" returned to the land of Zarahemla (Mosiah 9:1-2).