Tuisto or Tuisco was according to Tacitus (Germania, ch. 2) the ancestor of all Germanic tribes. He was the father of the first man, Mannus. He was worshipped with human sacrifice. According to Jakob Grimm, his name and variant forms (Thuisco, Thuiskon, Tuisco) come from the adjective tivisco derived from the name of the god Tiu; the name Tiu in turn derives from the Proto-Indo-European root *dyeu meaning "daylight sky" (the names of many other deities also derive from this root, such as Jupiter, Diana, Zeus, Dione, Tyr, Dyavaprthivi, Devi and Asmodai), and the adjective derived from it could meaning either "celestial" or "son of Tiu".
According to Jakob Grimm, his name and variant forms (Thuisco, Thuiskon, Tuisco) come from the adjective tivisco derived from the name of the god Tiu; the name Tiu, Proto-Germanic *Tîwaz, derives from Proto-Indo-European *Dyeus, the god of the daylit sky, and the adjective derived from it could mean either "celestial" or "son of Tiu".
If so Tuisto could be the same being as the primeval giant Ymir who was a hermaphrodite that procreated the first race.
Tuisto is the creator-god worshipped by early Celts.
Caesar describes the Celtic creatorgod in the sixth book of De Bello Gallico and states Tuisto is to be compared with Dis or Dui(s), the Roman god of darkness, commonly known as Pluto.
The Celtic creatorgod Tuisto is equivalent to the biblical God Jahweh (Yahweh), written as the sacred word (tetragrammaton) in four letters IHVH, in which the hieroglyphical character I symbolizes the male, and V symbolizes the female side of the androgyne God Jahweh.