Libertarian: Metaphysical stance directly opposed to the notion that thoughts, feelings and human behaviour are predetermined along with the rest of the universe. Free will is real and therefore determinism must be false. We are the authors of our actions. See Roderick Milton Chisholm, Robert Kane, Immanuel Kant, René Descartes, etc.

Compatibilist: We can subscribe to both free will and determinism without being inconsistent or contradictory. Most compatibilists do not support libertarian Liberum arbitrium, believing instead that the illusion of free will is strong enough to behave as though people have absolute autonomy and should be held accountable for their actions (a soft determinism emphasising responsibility). See Daniel Dennett, Matt Dillahunty, John Martin Fischer, Thomas Hobbes, etc.

Hard Determinist: The philosophical view that we live in a cause-and-effect universe through and through and since we are also made of atoms and molecules obeying the laws of physics, free will is absurd and merely illusory. Ultimately, nobody is to be praised or blamed for their actions (so criminals should be detained but retributive justice is unwarranted or morally indefensible). See John Locke, Baruch Spinoza, Sam Harris, Gregg Caruso, etc.