| Conn O'Neill Conn Ó Néill | |
| Death Date: | December 1601 |
| Death Place: | Tír Eoghain, Ulster, Ireland |
| Other Names: | Conn Mac An Iarla |
| Birth Date: | Between 1569–1574 |
| Birth Place: | Likely Ulster, Ireland |
| Mother: | Daughter of Brian McPhelim O'Neill |
| Noble Family: | O'Neill dynasty |
| Father: | Hugh O'Neill, Earl of Tyrone |
Conn O'Neill (; –1601), known as Conn Mac An Iarla ("son of the Earl"), was an Irish soldier of noble ancestry. The eldest son of Gaelic lord Hugh O'Neill, he fought for his father in the Nine Years' War. Historian Paul Walsh described Conn as a "capable soldier".
Conn was the oldest son of Gaelic Irish lord Hugh O'Neill (Earl of Tyrone, 1585–1613), and his first wife, who was a daughter of Brian McPhelim O'Neill of Clandeboye. Conn's mother was possibly named Katherine[1] or Feodora. He had at least one full-sister, who married Sir Ross McMahon around 1579. Tyrone also had another daughter, possibly a full-sibling of Conn, named Rose.
When his grandfather Brian was incriminated in a violent conflict with English colonists, his father Tyrone withdrew any association with Brian by annulling the marriage on grounds of consanguinity. The case was judged in Tyrone's favour by the Archbishop, Official and Registrar of Armagh. The children of this marriage were therefore shut out from Tyrone’s noble lineage, and Conn was considered illegitimate by English society. The eldest son of Tyrone's subsequent marriage, Hugh (–1609),[2] was considered his heir.
The Royal Society of Antiquaries of Ireland suggests Conn's birthdate was, however by this time his father Tyrone had already remarried to his second wife Siobhán O'Donnell. Conn's birthdate was prior to his father's annulment, meaning he was born sometime between 1569 and 1574.
At the start of the Nine Years' War Tyrone sent Conn on a raid into Monaghan.[3] When Tyrone went into open rebellion in early 1595, Conn was one of his most "efficient" captains. That year he took possession of Fort Monaghan.
In 1599, Conn commanded 300 men. He organised a riverside conference with the English on 7 September 1599. He was wounded near Kilmallock in 1600. In 1601, he was at the head of 20 cavaliers and 100 foot soldiers. On 9 December, it was reported that "Con, Tyrone's base son, is lately dead in [<nowiki/>[[Tír Eoghain]]]".
Conn's son, Feardorcha, took part in the Flight of the Earls, leaving Ireland for mainland Europe.