The significant leader known as "the Great Emancipator" is Abraham Lincoln. He earned this title for his crucial role in the abolition of slavery in the United States. Lincoln's issuance of the Emancipation Proclamation in 1863 declared the freedom of enslaved people in Confederate states. His commitment to the restoration of the Union during the Civil War and his moral stance against slavery were pivotal, leading to the passage of the Thirteenth Amendment, which officially abolished slavery in the U.S.