1155 (MCLV) was a common year starting on Saturday of the Julian calendar, the 1155th year of the Common Era (CE) and Anno Domini (AD) designations, the 155th year of the 2nd millennium, the 55th year of the 12th century, and the 6th year of the 1150s decade. As of the start of 1155, the Gregorian calendar was 7 days ahead of the Julian calendar, which was the dominant calendar of the time.

• February 28 – Henry the Young King, son of Henry II of England (died 1183)
• May 17 – Jien, Japanese poet and historian (died 1225)
• November 11 – King Alfonso VIII of Castile (died 1214)
• Saito Musashibo Benkei, Japanese fighting monk
• Kamo no Chomei, Japanese writer (died 1216)
• Shahab-ud-din Suhrawardi, a Sufi saint and mystic of Islam.