The Book of Enoch is traditionally regarded to be the work of Enoch, the great-grandfather of Noah. It is canonical in the Ethiopian Orthodox Church and Eritrean Orthodox Church. Enoch was read by many early Christians, and Jude quotes the book in Jude 1:14-15
"And Enoch also, the seventh from Adam, prophesied of these men, saying, Behold, YHWH cometh with ten thousands of his saints, To execute judgment upon all, and to convince all that are ungodly among them of all their ungodly deeds which they have ungodly committed, and of all their hard speeches which ungodly sinners have spoken against him." (1 Enoch 1:9)
Major Events from the Book of Enoch are also quoted in Genesis 6:1-4
"Now it came about, when men began to multiply on the face of the land, and daughters were born to them, that the sons of God saw that the daughters of men were beautiful and they took wives for themselves, whomever they chose. Then YHWH said, "My Spirit shall not strive with man forever, because he also is flesh nevertheless his days shall be one hundred and twenty years." The Nephilim were on the earth in those days, and also afterward, when the sons of God came in to the daughters of men, and they bore children to them. Those were the mighty men who were of old, men of renown."