Friedrich Heinrich Jacobi was a German philosopher, writer and socialite. He is best known for popularizing the concept of nihilism, denigrating it as the necessary result of Enlightenment thought and the philosophical systems of Baruch Spinoza, Immanuel Kant, Johann Gottlieb Fichte and Friedrich Wilhelm Joseph Schelling.
Jacobi advocated Glaube and Offenbarung instead of speculative reason. According to one view, Jacobi can be seen to have anticipated present-day writers who criticize secular philosophy as relativistic and dangerous for religious faith. His aloofness from the Sturm and Drang movement was the basis of a brief friendship with Johann Wolfgang von Goethe.
He was the younger brother of poet Johann Georg Jacobi and the father of the psychiatrist Maximilian Jacobi.