Year 984 (CMLXXXIV) was a leap year starting on Tuesday of the Julian calendar.

• Spring – German boy-king Otto III (4 years old) is seized by the deposed Henry II, Duke of Bavaria ("the Wrangler"), who has recovered his duchy and claims the regency as a member of the Ottonian Dynasty. But Henry is forced to hand over Otto to his mother, empress consort Theophanu.^[1]
• King Ramiro III of León loses his throne to Bermudo II (the rival king of Galicia), who also becomes ruler of the entire Kingdom of León (modern-day Spain).

• Fall – Emperor En'yū abdicates the throne in favor of his 16-year-old son Kazan after a 15-year reign. En'yū retires and becomes a Buddhist priest.

• Qiao Weiyue, a Chinese engineer, innovates the first known use of the double-gated canal pound lock during the Song dynasty, for adjusting different water levels in segments of the Grand Canal in China.

• August 20 – Pope John XIV dies a prisoner in the Castel Sant'Angelo at Rome after a 1-year reign, having either been murdered or starved to death.^[2]
• Anti-Pope Boniface VII returns from Constantinople and gains support from the powerful Roman Crescentii family. He takes hold of the papal throne.

• Abu al-Qasim Muhammad ibn Abbad, founder of the Abbadid dynasty (d. 1042)
• Choe Chung, Korean Confucian scholar and poet (d. 1068)
• Emma of Normandy, noblewoman, queen consort of England (twice), Denmark and Norway (d. 1052; approximate date)

• July 7 – Crescentius the Elder, Roman politician and aristocrat
• July 18 – Dietrich I, bishop of Metz
• August 1 – Æthelwold, bishop of Winchester
• August 20 – John XIV, pope of the Catholic Church
• September 9 – Warin, archbishop of Cologne
• Buluggin ibn Ziri, ruler (emir) of the Zirid Dynasty
• Domnall Claen, king of Leinster (Ireland)
• Edith of Wilton, English princess and abbess
• Eochaid Ua Floinn, Irish poet (approximate date)
• Gerberga, Frankish queen (approximate date)
• Jordan, bishop of Poland (or 982)
• Miró III, count of Cerdanya and Besalú (b. 920)
• Ragnhild Eriksdotter, Norse Viking noblewoman
• Shi Shouxin, Chinese general (b. 928)