Ja'far bin Yahya Barmaki, Jafar al-Barmaki (Persian: جعفر بن یحیی برمکی, Arabic: جعفر بن يحيى, ja`far bin yaḥyā) (767–803) was the son of a Persian Vizier (Yahya ibn Khalid) of the Arab Abbasid Caliph, Harun al-Rashid, from whom he inherited that position. He was a member of the influential Barmakids family. He was beheaded in 803 for allegedly having an affair with Harun al-Rashid's sister Abbasa.
He had a reputation as a patron of the sciences, and did much to introduce Greek science into Baghdad, attracting scholars from the nearby Academy of Gundishapur to help translate Persian works into Arabic (the so-called "Translation Movement"). He was also credited with convincing the caliph to open a paper mill in Baghdad, the secret of papermaking had been obtained from Chinese prisoners at the Battle of Talas, in present day Kyrgyzstan in 751.
Ja'far also appears (under the name of Giafar in most translations) along with Harun al-Rashid in several Arabian Nights tales, often acting as a protagonist. In "The Three Apples" for example, Ja'far is like a detective who must solve a murder mystery and find the culprit behind the murder, and in "The Tale of Attaf", Ja'far is more of an adventurer. In "'The Tyrant of Bagdad'", by Glenn Pierce "Glenn Dumke", Ja'fars story is told in a fictional account of Charlemagne's ambassador's travel to meet with Harun al-Rashid.
However, more recent media inspired by the Arabian Nights has portrayed Ja'far as both a villain and a sorcerer: