The first was the son of Cain. Cain later founded a city which he named Enoch.
The second was the son of Jared, father of Methuselah, grandfather of Lamech and the great-grandfather of Noah. Genesis 5:24 tells us, "Enoch walked with God; then he was no more, because God took him away".
In the new testament Jude quotes Enoch as prophesying a day of judgement. According to the LDS Church's Pearl of Great Price, this Enoch founded the righteous city of Zion in a very wicked world. He and the entire city's inhabitants were "translated" by God and vanished from the presence of the earth before the Great Flood. Methuselah and his family (including Noah) were left behind so that righteous people could still populate the earth.
In the Quran, the prophet Enoch is known as Idris.
External link
Dictionary of the History of Ideas: (http://etext.lib.virginia.edu/cgi-local/DHI/dhi.cgi?id=dv1-65) Cosmic Voyages