Paul Jakob Deussen (German: ['pa?l 'ja?kop 'd??s?n]; 7 January 1845 – 6 July 1919) was a German Indologist and professor of Philosophy at University of Kiel.
Strongly influenced by Arthur Schopenhauer, Deussen was a friend of Friedrich Nietzsche and Swami Vivekananda.
In 1911, he founded the Schopenhauer Society (Schopenhauer-Gesellschaft).
Professor Deussen was the first editor, in 1912, of the scholarly journal Schopenhauer Yearbook (Schopenhauer-Jahrbuch).
Deussen, who Sanskritised his name to "Deva-Sena" as a mark of his admiration for Hinduism, is one of the distinguished roll of Europeans who — often with lyrical admiration — participated in the scholarly Western discovery of Sanskrit and Hinduism that took place in British India itself, Germany, France and England.