1158 (MCLVIII) was a common year starting on Wednesday of the Julian calendar, the 1158th year of the Common Era (CE) and Anno Domini (AD) designations, the 158th year of the 2ndmillennium, the 58th year of the 12thcentury, and the 9th year of the 1150s decade. As of the start of 1158, the Gregorian calendar was 7 days ahead of the Julian calendar, which was the dominant calendar of the time.

• August 6 – Al-Nasir li-Din Allah, Abbasid caliph (d. 1225)
• September 23 – Geoffrey II, duke of Brittany (d. 1186)
• Albert I (the Proud), margrave of Meissen (d. 1195)
• Baldwin of Bethune, French nobleman (d. 1212)
• Ermengol VIII (or Armengol), count of Urgell (d. 1208)
• Fujiwara no Ietaka, Japanese (waka) poet (d. 1237)
• Giordano Forzatè, Italian religious leader (d. 1248)
• Henry I, French nobleman and knight (d. 1190)
• Henry I (the Elder), German nobleman (d. 1223)
• Jinul (or Chinul), Korean Zen Master (d. 1210)
• Margaret of France, daughter of Louis VII (d. 1197)
• Philip of Dreux, bishop of Beauvais (d. 1217)
• Satō Tsugunobu, Japanese warrior (d. 1185)
• Taira no Shigehira, Japanese general (d. 1185)
• Theobald I, French nobleman and knight (d. 1214)
• Valdemar Knudsen, Danish bishop (d. 1236)
• Yvette of Huy, Belgian anchoress (d. 1228)

• April 26 – Martirius, archbishop of Esztergom
• July 19 – Wibald, German monk and abbot (b. 1098)
• July 27 – Geoffrey VI, count of Nantes (b. 1134)
• August 20 – Rögnvald Kali Kolsson, Earl of Orkney
• August 31 – Sancho III, king of Castile (b. 1134)
• September 22 – Otto I, German bishop (b. 1114)
• December 15 – Frederick II, German archbishop
• Abu Jafar ibn Atiyya, Almohad vizier and writer
• Anselm of Havelberg, German bishop (b. 1100)
• Barthélemy de Jur, French bishop (b. 1080)
• Oda of Brabant, Belgian prioress and saint
• Thorbjorn Thorsteinsson, Norwegian pirate