A Population III star belongs to the first generation ever to form, condensing from gas that held only hydrogen, helium, and a trace of lithium left by the Big Bang. Without heavier elements to help the gas cool and fragment, theory suggests they grew far more massive than stars today, burned ferociously, and died young. Their supernovae seeded the universe with the first heavy elements, making every later generation possible. None has ever been observed directly, and finding one is among the headline goals of JWST.