Lucifer is a name for the Devil — the great enemy in Christian stories, the one who rebelled and fell. In churches, books and everyday talk that still uses those pictures, Lucifer and Satan often point to the same figure, though some writers keep the names for different moments of the story. Though actually, the name first meant “light-bearer” in Latin, and it was also a name for the morning star (the planet we call Venus when it shines before dawn). The Devil sense probably grew from a reading of a line in Isaiah about a fallen “morning star”. English once had its own translation, “lightbearer”, but Lucifer won. Today, outside religion and literature, people mainly know it as a dramatic name for the Devil — and from comics, TV and posters. It is a proper name, so it takes a capital L.