|1128 by topic|
|Birth and death categories|
|Births – Deaths|
|Establishments and disestablishments categories|
|Establishments – Disestablishments|
|Art and literature|
|1128 in poetry|
|Ab urbe condita||1881|
|Balinese saka calendar||1049–1050|
|English Regnal year||28 Hen. 1 – 29 Hen. 1|
|Chinese calendar||丁未年 (Fire Goat)|
3824 or 3764
— to —
戊申年 (Earth Monkey)
3825 or 3765
|- Vikram Samvat||1184–1185|
|- Shaka Samvat||1049–1050|
|- Kali Yuga||4228–4229|
|Japanese calendar||Daiji 3|
|Minguo calendar||784 before ROC|
|Seleucid era||1439/1440 AG|
|Thai solar calendar||1670–1671|
1254 or 873 or 101
— to —
1255 or 874 or 102
Year 1128 (MCXXVIII) was a leap year starting on Sunday (link will display the full calendar) of the Julian calendar.
- Byzantine–Hungarian War: Emperor John II (Komnenos) defeats the Hungarians and their Serbian allies at the fortress of Haram (or Chramon), which is modern-day Nova Palanka. 
- June 24 – Battle of São Mamede: Count Alfonso I (Henriques) defeats the forces led by his mother, Queen Theresa of Portugal, near Guimarães, and gains control of the county. Alfonso styles himself "Prince of Portugal".
- June 29 – Conrad III, anti-king of Germany, is crowned "King of Italy" by Archbishop Anselmo della Pusterla at Monza in Lombardy.
- July 27 – The city of Bruges (modern Belgium) is founded. It receives its city charter – as well new walls and canals are built.
- Pope Honorius II invests Roger II of Sicily as duke of Apulia at Benevento, after his failure to form an coalition against Roger.
- King Louis VI (the Fat) of France agrees to the accession of Thierry of Alsace (or Theoderic), as count of Flanders.
- June 17 – King Henry I marries his only legitimate daughter, dowager Empress Matilda, to the 14-year-old Geoffrey V (the Fair), count of Anjou.
- Hugues de Payens, French Grand Master of the Order of the Knights Templar, visits both England and Scotland, where he raises men and money for the Order.
- Jin–Song War: Emperor Gao Zong of the Song Dynasty establishes a new capital at Yangzhou, while the government retreats south, after Jurchen forces capture the previous capital of Kaifeng, in the Jingkang Incident.
- Forces of the Kingdom of Champa invade Vietnam.
- November 24 – Waverley Abbey is founded by Bishop William Giffard. The first abbot and 12 Cistercian monks are brought from L'Aumône Abbey in Normandy.
- Honorius II recognizes and confirms the Order of the Knights Templar. The French abbot Bernard of Clairvaux codifies the rule of the Order.
- Holyrood Abbey is founded in Edinburgh by King David I of Scotland.
- Kelso Abbey is founded by Scottish monks of the Tironensian Order.
- March 18 – Stephen of Tournai, French bishop (d. 1203)
- Absalon, Danish archbishop and statesman (d. 1201)
- Adolf II, count of Schauenburg and Holstein (d. 1164)
- Alain de Lille, French theologian and poet (approximate date)
- Ali ibn Muhammad ibn al-Walid, Arab theologian (d. 1215)
- Constance of Hauteville, princess of Antioch (d. 1163)
- John Doukas (Komnenos), Byzantine governor (d. 1176)
- John Kontostephanos, Byzantine aristocrat (approximate date)
- Lorcán Ua Tuathail, Irish archbishop of Dublin (d. 1180)
- Ludwig II (the Iron), landgrave of Thuringia (d. 1172)
- Muhammad II ibn Mahmud, Seljuk sultan (d. 1159)
- Ruzbihan Baqli, Persian poet and mystic (d. 1209)
- Taira no Norimori, Japanese nobleman (d. 1185)
- January 1 – Albero I, prince-bishop of Liège (b. 1070)
- February 12 – Toghtekin, Turkish ruler of Damascus
- June 2 – Pier Leoni (or Petrus Leo), Roman consul
- July 28 – William Clito, count of Flanders (b. 1102)
- September 5 – Ranulf Flambard, bishop of Durham
- December 4 – Henry II, German nobleman (b. 1102)
- December 15 – Fulco I d'Este, Lombard nobleman
- Abu Ibrahim ibn Barun, Andalusian Jewish rabbi
- Conaing Ua Beigléighinn, Irish monk and abbot
- Constantine I of Torres, ruler (judge) of Logudoro
- Fujiwara no Kiyohira, Japanese nobleman (b. 1056)
- Geoffrey Brito (or le Breton), archbishop of Rouen
- Ibn Tumart, Almoravid political leader (or 1130)
- Jimena Muñoz (or Muñiz), Spanish noblewoman
- Rogvolod Vseslavich (Boris), prince of Polotsk
- Warmund (or Gormond), patriarch of Jerusalem
- ^ Angold, Michael (1997). The Byzantine Empire, 1025–1204: A Political History, p. 153. ISBN 978-0-5822-9468-4.
- ^ Coedès, George (1968). Walter F. Vella (ed). The Indianized States of Southeast Asia, pp. 140–141. Trans. Susan Brown Cowing. University of Hawaii Press. ISBN 978-0-8248-0368-1.
- ^ H.E. Malden, ed. (1967). 'House of Cistercian monks: Abbey of waverley', A History of the County of Surrey: Volume 2. Victoria County History. pp. 77–89.
- ^ Fletcher, R. A. (1987). "Reconquest and Crusade in Spain c. 1050-1150". Transactions of the Royal Historical Society. 5. 37: 31–47 . JSTOR 3679149.