Despite the popular mythology about a wicked angel called Lucifer, the word only occurs once in the Bible and it has nothing to do with angels. The name Lucifer comes from Isaiah 14:12 which says (in the KJV)
How art thou fallen from heaven, O Lucifer, son of the morning…
This is the only place in the Bible where the word Lucifer occurs and it does not occur at all in most modern versions. If you look back to verse 4 it is clear that this passage is about the king of Babylon! Also Isaiah 14:16-17 calls him a “man” — not a fallen angel! So how did the name become associated with an angel?
Lucifer is a Latin word meaning the “morning star” or Venus, the brightest object in the sky just before dawn. In fact, modern versions translate the word as “morning star”. The king of Babylon was very proud and imagined himself to be a god. He said “I will make myself like the Most High” (v14) and apparently thought of himself as being “in heaven” like Venus. Instead, he fell to the earth in defeat. Isaiah describes him as a metaphorical morning star — appearing bright and elevated, but about to plunge below the horizon and disappear.
A similar passage is Ezekiel 28 which is about the king of Tyre, although it is also often incorrectly interpreted as applying to a wicked angel.