Year 836 (DCCCXXXVI) was a leap year starting on Saturday of the Julian calendar, the 836th year of the Common Era (CE) and Anno Domini (AD) designations, the 836th year of the 1st millennium, the 36th year of the 9th century, and the 7th year of the 830s decade.

• Driven by tensions between his favoured Turkish guard and the populace of Baghdad, Abbasid caliph al-Mu'tasim moves his residence to the new city of Samarra, 130 km north of Baghdad. With brief interruptions, the city will remain the seat of the Abbasid caliphs until 892.

• Battle of Carhampton: Danish Vikings arrive in the Wessex areas of Somerset and North Devon. Ecgberht, King of Wessex fights them but is forced to withdraw.^[1]

• July 4 – Pactum Sicardi: Prince Sicard of Benevento signs a 5-year armistice with the duchies of Sorrento, Naples and Amalfi. He recognizes the trade of merchants among the three cities in Southern Italy.
• Malamir, ruler (khan) of the Bulgarian Empire, dies after a 4-year reign and is succeeded by his nephew Presian I. Because of his young age and inexperience, the Bulgarian state affairs are dominated by his minister and commander-in-chief Isbul.
• Pietro Tradonico is appointed doge of Venice (until 864).
• The oldest known mention is made of the city of Soest (modern Germany).

• The Basilica of St. Castor in Koblenz (Rhineland-Pfalz) is constructed.

• Æthelberht, king of Wessex (approximate date)
• Al-Musta'in, Muslim caliph (d. 866)
• Fujiwara no Mototsune, Japanese regent (d. 891)
• Ibn al-Rumi, Muslim poet (d. 896)
• Luo Hongxin, Chinese warlord (d. 898)
• Mihira Bhoja, king of the Gurjara-Pratihara Dynasty (d. 885)
• Wei Zhuang, Chinese poet (approximate date)

• March 17 – Haito, bishop of Basel
• Adalram, archbishop of Salzburg
• Aznar Sánchez, duke of Gascony
• Herefrith, bishop of Winchester
• Heungdeok, king of Silla (b. 777)
• Lambert I, Frankish nobleman
• Malamir, ruler of the Bulgarian Empire
• Matfrid, Frankish nobleman
• Muhammad ibn Idris, Idrisid emir of Morocco^[2]
• Nicetas the Patrician, Byzantine official
• Prosigoj, Serbian prince (approximate date)
• Ralpacan, emperor of Tibet (b. 802)
• Wala of Corbie, Frankish nobleman
• Wang Zhixing, general of the Tang Dynasty (b. 758)