The Levellers were a political movement of the 1640s, active during the English Civil Wars, that argued for popular sovereignty, a much wider franchise, religious toleration and equality before the law, at a moment when the war's outcome had left the question of where ultimate authority lay genuinely open. John Lilburne was its best known leader.
The movement's clearest statement of its programme was the Agreement of the People, drafted in 1647 as a proposed written constitution to replace the settlement Parliament and the army leadership were negotiating. It was debated directly inside the New Model Army at the Putney Debates of October and November 1647, where Leveller-aligned soldiers and officers such as Thomas Rainsborough argued for near-universal manhood suffrage against army commanders including Henry Ireton, who wanted the vote confined to men of property.
The Levellers lost that argument. Cromwell suppressed Leveller-led mutinies inside the army, at Corkbush Field in November 1647 and more decisively at Burford in May 1649, ending the movement as an organised force. Its core claims, that legitimate government rests on the consent of the governed and that rights belong to people rather than to property, outlived its defeat and were picked up by later constitutional and democratic thought far beyond the specific settlement it had failed to win.