Samyaza (also written Semjâzâ, Semyaza, Shemihazah, Samiaza, and several other transliterations depending on the manuscript tradition) is named in 1 Enoch as the principal leader of the two hundred Watchers who descended at Mount Hermon. The name probably means 'the Name has seen' or 'my name has seen' — a deliberate irony given that the rebellion is fundamentally against the One whose Name is invoked.
1 Enoch 6:3–4 records his proposal: 'And Samyaza, who was their leader, said unto them: I fear that perhaps you will not consent to do this deed, and I alone shall have to pay the penalty of a great sin.' His solution is the binding oath. He requires the two hundred to swear together so that none can withdraw at the last moment and shift the punishment onto him alone. The oath is sworn on Mount Hermon — and the Hebrew root of Hermon (ḥrm) carries the sense of 'curse' or 'devoted-to-destruction,' which the text seems to register as a grim play on words. The very mountain where the oath is sworn becomes a witness to the curse the oath invokes.
His specific corruption-teaching, according to 1 Enoch 7, is the act of taking human wives itself — and the production of offspring with them. He is therefore directly responsible for the Nephilim, the giants whose violence floods the earth and provokes the Deluge. Other Watchers under him taught the various arts of war, cosmetics, divination, and metallurgy; Samyaza's specific portfolio is the genealogical corruption.
His punishment is recorded in 1 Enoch 10:11–14. God commands Michael: 'Go, bind Samyaza and his associates who have united themselves with women so as to have defiled themselves with them in all their uncleanness. And when their sons have slain one another, and they have seen the destruction of their beloved ones, bind them fast for seventy generations in the valleys of the earth, till the day of their judgment and of their consummation, till the judgment that is for ever and ever is consummated.' The temporal sentence — 'seventy generations' — frames the rebellion within a cosmological clock that ends at the eschaton, and the punishment is doubled: bound in the earth and forced to witness the mutual destruction of their offspring.
Samyaza appears in nearly every list of fallen-angel ringleaders across Second Temple, rabbinic, and Christian apocryphal literature. The Book of Jubilees (4:15) preserves an alternative version of the descent in which the Watchers were initially sent down for good purposes — 'to do judgment and uprightness on the earth' — and only fell after arriving. Patristic interpretation tended to harden the picture: Samyaza becomes a fixed figure of premeditated rebellion, the angelic counterpart to the Pharaoh of Exodus or the Nebuchadnezzar of Daniel — the visible captain of an organized opposition to God's purpose for creation.