Ivan Karamazov is a central character in Fyodor Dostoevsky's novel, "The Brothers Karamazov." He is the intellectual and philosophical son of Fyodor Karamazov, known for his deep questioning of morality, faith, and the existence of God. Ivan struggles with the concept of free will and the suffering of innocent people, which leads him to a crisis of faith. Throughout the novel, Ivan's internal conflict is highlighted in his famous "Rebellion" chapter, where he challenges the idea of a just God in light of human suffering. His character represents the struggle between rational thought and spiritual belief, making him a pivotal figure in the exploration of existential themes in the story.