|Covid-19|March 1 – Diego Rodríguez Porcelos, count of Castile, founds and repopulates (repoblación) Burgos and Ubierna (Northern Spain), under the mandate of King Alfonso III of Asturias.
Summer – King Carloman II reverts to the former fall-back of 'pay and pray', buying (with Danegeld) a truce at Amiens, while he raises 12,000 lbs of silver for the Vikings to depart.
December 12 – Carloman II dies after a hunting accident. He is succeeded by his cousin, Emperor Charles the Fat, who for the last time reunites the Frankish Empire.
King Æthelred II of Mercia marries Princess Æthelflæd, daughter of King Alfred the Great. He accepts Wessex overlordship, and demotes himself to become "Lord of the Mercians".
January 6 – Hasan ibn Zayd, founder of the Zaydid Dynasty, dies after a 20-year reign at Amul. He is succeeded by his brother Muhammad, as emir of Tabaristan.
May 10 – Ahmad ibn Tulun, founder of the Tulunid Dynasty, dies after a 15-year reign. He is succeeded by his son Khumarawayh, as ruler of Egypt and Syria.
Fall – The Arabs sack in two raids (September and November) the abbey of Monte Cassino. The bulk of the monastic community flee to Teano (Campania).
March 4 – Emperor Yōzei is forced to abdicate the throne by Fujiwara no Mototsune, chancellor (kampaku) of the Japanese royal court. He is succeeded by his great-uncle Kōkō.
The Huang Chao rebellion is suppressed by forces of Emperor Xi Zong, with the help of the Shatuo Turks. Chinese warlords rule the country, instead of the imperial government.
May 15 – Pope Martinus II dies at Rome, after a reign of less than 1½ years. He is succeeded by Adrian III (also referred to as Hadrian III), as the 109th pope of the Catholic Church.
Burchard II, duke of Swabia (or 883)
Kong Xun, Chinese general and governor (d. 931)
Zhang Yanhan, Chinese official and chancellor (d. 941)
January 6 – Hasan ibn Zayd, Muslim emir of Tabaristan
May 10 – Ahmad ibn Tulun, Muslim governor (b. 835)
May 15 – Martinus II, pope of the Catholic Church
June 11 – Shi Jingsi, general of the Tang Dynasty
June 29 – Yang Shili, general of the Tang Dynasty
July 13 – Huang Chao, Chinese rebel leader (b. 835)
October 12 – Tsunesada, Japanese prince (b. 825)
December 12 – Carloman II, king of the West Frankish Kingdom
Al-Abbas ibn Ahmad ibn Tulun, Muslim usurper
Colcu mac Connacan, Irish abbot and historian
Dawud al-Zahiri, Muslim scholar (or 883)
Domnall mac Muirecáin, king of Leinster
Li Changyan, Chinese warlord and governor
Shang Rang, Chinese rebel leader (approximate date)
Wang Duo, chancellor of the Tang Dynasty
Zhou Ji, Chinese warlord (approximate date)
Year 884 (DCCCLXXXIV) was a leap year starting on Wednesday (link will display the full calendar) of the Julian calendar.