John Stuart Mill, 1806-1873, was the most famous classical liberal, a British philosopher and a political economist whose concept of liberty justified the freedom of the individual in opposition to unlimited state control. His hierarchy of pleasures in Utilitarianism was a notable idea. He felt that individual accomplishment through self-improvement was the source of true freedom.
Herbert Spencer, 1820-1903, was a prominent classical liberal political theorist of the Victorian era. As a polymath, he had an enormous range of knowledge. He achieved unparalleled popularity. Spencer was a Utilitarian, feeling that the promotion of human survival would maximize human utility. Spencer is associated with Social Darwinism, perhaps because he supported competition, but he did not embrace Darwinist science.
Lysander Spooner, 1808-1887, was an American individualist anarchist and abolitionist. His key contribution was to demolish consent theories. In the No Treason pamphlets he asks for names of those who have actually consented to the Constitution.
Lecture 8 of 10 from David Gordon's The History of Politcal Philosophy: From Plato to Rothbard.