The protagonist of John Milton's "Paradise Lost" is Satan, also known as Lucifer. The epic poem tells the story of the fall of man through Adam and Eve's disobedience to God in the Garden of Eden. However, instead of focusing on Adam and Eve as central figures, Milton chooses to make Satan the main character or hero (anti-hero) who rebels against God and leads a failed rebellion against Heaven. Throughout the poem, Satan is portrayed as complex and multifaceted with his own motivations, desires, and justifications for his actions.