South American Indians who once inhabited the island of Tierra del Fuego. They were historically divided into two major sections: Shelknam and Haush. They spoke different dialects and had slightly different cultures. The Ona were hunters and gatherers who subsisted chiefly on guanaco, small herds of which were stalked by bowmen; on various small animals; and on shellfish, cormorants, and berries.

They were organized in patrilineal bands of 40 to 120 members, each claiming territorial rights to a well-defined hunting area. The men married women from other bands. The nomadic life of the Ona resembled that of the Patagonian and Pampean hunters more than that of their immediate neighbours of the Chilean archipelago except for social and religious ceremonials. The Ona celebrated male initiation rites, klóketen; secrets were revealed by the older men to the younger, and women were excluded from them. The rites were based on a myth that told how the men had overturned a previous regime dominated by women. They believed in a supreme being, who sent punishment and death for wrongdoing. Shamans, who aided hunters and cured sickness, derived their power from the spirits of deceased shamans who appeared to them in dreams.