Lucifer is the clearest case in this collection of a name created by a translation, and the whole of it can be traced in one verse.
Isaiah 14:12 in Hebrew reads: how you have fallen from heaven, helel ben shachar, shining one, son of the dawn. The chapter is explicitly framed: verse 4 says this is a taunt to be taken up against the king of Babylon. It mocks a specific human ruler for imperial arrogance, says he will be brought down to Sheol, and taunts him that he will not even get a decent burial. It is a political poem.
The Greek Septuagint rendered helel as heosphoros, dawn-bringer. Jerome, translating into Latin around 400, used lucifer, light-bearer, which was the ordinary Latin word for the morning star, the planet Venus seen before sunrise. It was not a name. Latin writers used it of the planet, and early Christians used it approvingly: there was a fourth-century bishop of Cagliari called Lucifer, venerated in some quarters as a saint, and the term is applied to Christ in the Latin of Second Peter 1:19 and in the Easter Exsultet, which sings of Christ as the true morning star.
Between roughly the second and fifth centuries, Christian writers, Origen and Tertullian among them, read the Isaiah passage as describing the fall of Satan behind the figure of the king. Once that reading held, the Latin common noun in the verse was available to be taken as the fallen angel's personal name, and English translations in the Wycliffe and King James tradition capitalised it.
Jewish interpretation has never read Isaiah 14 as being about a fallen angel.