800s births

Abū Yūsuf Yaʻqūb ibn ʼIsḥāq aṣ-Ṣabbāḥ al-Kindī (; ; ; ) was an Arab polymath who was active as a philosopher, mathematician, physician, and music theorist. Al-Kindi was the first of the Islamic peripatetic philosophers, and is hailed as the "father of Arab philosophy".

pope

Arab Christian scholar, physician and scientist (809–873)

Tritsuk Detsen (), better known by his nickname Ralpachen (; 802–838), was the 40th King (Tsenpo) of Tibet from 815 to 838. He reigned after the death of his father, Sadnalegs, and grew the empire to its largest extent. He was murdered by his younger brother Langdarma in 838. Ralpachen is one of the "Three Dharma Kings of Tibet", and referred to as "son of God" in the ancient Tibetan chronicle Testament of Ba.

Nominoe or Nomenoe (; ; c 800,  7 March 851) was the first Duke of Brittany from 846 to his death. He is the Breton pater patriae and to Breton nationalists he is known as '''' ("father of the country").

Carolingian priest (ca. 808–849)

thumb|One view about the borders of the Principality of Nitra around 833

doge of Venice

Emma of Altdorf, also known as Hemma ( – 31 January 876), a member of the Elder House of Welf, was Queen consort of East Francia by marriage to King Louis the German, from 843 until her death.

German theologian

Swithun (or Swithin; ; ; died 2 July 863) was an Anglo-Saxon bishop of Winchester and subsequently patron saint of Winchester Cathedral. His historical importance as bishop is overshadowed by his reputation for posthumous miracle-working.

Carolingian priest and poet

Benedictine monk (c.805–c.862)

Frankish nobleman

9th-century Byzantine emperor

mathematician

Amoghavarsha Nrupatunga (–878), also known as Amoghavarsha I, was the Rashtrakuta emperor from 814 until his death in 878. He is considered by many historians to be the greatest emperor of the Rashtrakuta dynasty. His reign of 64 years is one of the longest precisely dated monarchical reigns on record. Many Kannada and Sanskrit scholars prospered during his rule, including the great Indian Jain mathematician Mahaviracharya who wrote the Ganita-sara-samgraha, Shakatayan and Srivijaya (a Jain Kannada language theorist), as well as Jain Monks like Acharya Jinasena and Acharya Virasena, Acharya Gu

French count

Irish monk

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Bishop of Le Mans and saint

9th-century Count of Paris

Govindasvāmi (or Govindasvāmin, Govindaswami) (c. 800 – c. 860) was an Indian mathematical astronomer most famous for his Bhashya, a commentary on the Mahābhāskarīya of Bhāskara I, written around 830. The commentary contains many examples illustrating the use of a Sanskrit place-value system and the construction of a sine table.