1 Enoch 15:8, 11–12 (R. H. Charles, 1913; selected excerpt, editorial brackets omitted)c. 200 BC · Second Temple PseudepigraphaExcerpt or editorial summary: And now, the giants, who are produced from the spirits and flesh, shall be called evil spirits upon the earth, and on the earth shall be their dwelling... And the spirits of the giants afflict, oppress, destroy, attack, do battle, and work destruction on the earth, and cause trouble: they take no food, but nevertheless hunger and thirst, and cause offences. And these spirits shall rise up against the children of men and against the women, because they have proceeded from them.
Analysis: Within the Book of the Watchers, this passage identifies the dead giants' surviving spirits as evil spirits active on earth. Its relationship to every later use of 'unclean spirits' must be argued rather than assumed.
Tertullian, Apology §22c. AD 197 · Ante-Nicene PatristicExcerpt or editorial summary: Editorial summary: Tertullian says that certain angels fell voluntarily and produced a corrupt demonic brood condemned together with them.
Analysis: Tertullian is one early Latin witness to an angelic-fall account.