Sir Felim O'Neill of Kinard (died 1652) was an Irish nobleman who led the Irish Rebellion of 1641 in Ulster which began on October 22 1641. His first name is also translated from Gaelic as Phelim and Kinard as Caledon. He was a member of Confederate Ireland during the Wars of the Three Kingdoms, where he fought under his kinsman Owen Roe O'Neill. He was captured and executed during the Cromwellian conquest of Ireland in 1652.

A member of the famous O'Neill family, Sir Felim was the grandson of Sir Henry Oge O'Neill , one of the O'Neills who remained in Ulster after the Flight of the Earls despite the difficulties bought on by land confiscation and the Plantation of Ulster. O'Neill's family were from a minor branch of the O'Neill clan and had risen to prominence by siding with the English against the chief, Hugh O'Neill in the Nine Years War. In return for their service, Phelim O'Neill's family retained some estates around Kinard in Tyrone. O'Neill was a member of the Irish Parliament in the 1630s and trained as a lawyer at Kings Inns in London.

However, in common with many Irish Catholics, and especially Gaelic Irishmen, O'Neill felt threatened by the Protestant English government of Ireland. In particular, they were aggreived at Catholic's exclusion from Public Office and the continual confiscations of Catholic owned land. This fear reached its high point in the late 1630s and early 1640s, when Thomas Wentworth, a minister of Charles I, was known to be planning widespread new plantations. A crisis point was reached in 1641, when the Scottish Covenanters and English Long Parliament threatened to invade Ireland to finally subdue Catholicism there.

In this atmosphere of fear and paranoia, Phelim O'Neill became involved in a plot hatched by fellow Gaelic Irish Catholics from Ulster, to sieze Dublin and swiftly take over the other important towns of Ireland. After this, they planned to issue their demands for full rights for Catholics and Irish self government in the King's name. O'Neill's role was to take towns and fortified place in the north of the country. However, the plan to take Dublin was bungled by two conspirators, Maguire and MacMahon, who were captured by the authorities. O'Neill went ahead started the rebellion in the north, but quickly found that he could not control the Irish Catholic peasantry he had raised. These people, many of whom had been displaced during the Plantation of Ulster began attacking the Scottish and English Protestant settlers, leading to the massacres for which the rebellion is infamous. O'Neill, along with Rory O'Moore, then tried to march on Dublin, defeating a government force at Julianstown but failing to take Drogheda after a rather inept siege.

The rebellion quickly spread to the rest of Ireland. By the spring of 1642 only fortified Protestant enclaves, around Dublin, Cork and Derry, held out. King Charles I sent a large army to Ireland, which would probably have put down the rebellion, had the English Civil War not broken out. As it was, the Irish Catholic upper classes had breathing space to form the Irish Catholic Confederation, which acted as a de facto independent government of Ireland until 1649. Phelim O'Neill was a member of the Confederate's parliament, named the General Assembly, but was sidelined in the leadership of Irish Catholics by more wealthy landed magnates. On the military side, O'Neill was also sidelined, when his kinsman, Owen Roe O'Neill, a professional soldier, was made general of the Confederate's Ulster army. Phelim O'Neill was a cavalry commander in this force, and spent most of the next six years fighting against the Scottish Covenanter army that had landed in Ulster. He fought in the army's victory at the battle of Benburb.

In Confederate politics, O'Neill was a moderate, advocating a deal with Charles I and the English Royalists as a means of winning the war against the English Parliament and the Scottish Covenanters. In 1648, he voted for such a deal, The Second Ormonde Peace, splitting with Owen Roe O'Neill, who opposed it and most of the Ulsterr army. In the summer of that year, the Confederate armies fought among themselves over this issue, with the pro-Royalists prevailing.

However, this was not enough to stop Ireland being re-conquered by the New Model Army of Oliver Cromwell in 1649-53. The well trained and supplied Parliamentarians crushed all Confederate and Royalist resistance and imposed a harsh settlement on Irish Catholics. Anyone implicated in the rebellion of 1641 was held responsable for the massacres of Protestant civilians and executed. Phelim O'Neill could therefore expect little mercy.

In August 1652, O'Neill was executed by a High Court set up in Dublin by the Cromwell government.