Aelius Galenus or Claudius Galenus (September AD 129 - 199/217; Greek: Ga?????; Galenos; from adjective ?a?????; 'calm'); better known as Galen of Pergamon (modern-day Bergama; Turkey); was a prominent Roman (of Greek ethnicity) physician; surgeon and philosopher.

Arguably the most accomplished of all medical researchers of antiquity; Galen contributed greatly to the understanding of numerous scientific disciplines including anatomy; physiology; pathology; pharmacology and neurology; as well as philosophy and logic.

The first major translator of Galen into Arabic was the Syrian Christian Hunayn ibn Ishaq. Hunayn translated (c.830-870) 129 works of 'Jalinos' into Arabic. One of the Arabic translations; 鈥楰itab ila Aglooqan fi Shifa al Amraz'; which is extant in the Library of Ibn Sina Academy of Medieval Medicine and Sciences; is a masterpiece of all literary works of Galen.

Although they are hardly visible in the 鈥楪alenic corpus' as it stands; many works that were once attributed to Galen are now ascribed to a 鈥楶seudo-Galen' and rarely give any additional information about the author's identity.