Ó Máoilsheáchlainn of Clann Colman
The Ó Máoilsheáchlainns of the Kingdom of Mide (presently the counties of Meath, Westmeath, and parts of the counties of Dublin, Kildare, Offaly, Longford, and Louth, all now in Leinster, and part of County Cavan, now in Ulster) are descendants of the Southern Uí Néill. The first part of the name – ‘maol’ – means ‘devotee of’ and the second part – sheachlann- refers to St Secundinus McLoughlin Family Crestwho was known in Ireland as St Seachlann. Secundinus was a disciple of St Patrick.So the name in full means ‘descendent of the devotee of St Secundinus’.The devotee of St Secundinus that the name refers to was Malachy who was High King of Ireland from 980 AD to 1002. It was first Anglicised to O’Melaghlin before changing again this time to MacLoughlin in the late 17th century.

High Kings of Ireland of this family included:

- Conchobar mac Donnchada, reigned 819-833, with opposition.
- Máel Sechnaill mac Máele Ruanaid (aka Máel Sechnaill I), reigned 846-862.
- Flann Sinna, reigned 879-916.
- Donnchad Donn, reigned 919-944.
- Máel Sechnaill mac Domnaill (aka Máel Sechnaill II), reigned 980-1002;1014-1022.
The Ó Máoilsheáchlainns of Meath lost their lands and their power in the centuries following the Norman Invasion – their homeland of Meath even losing its status and being absorbed into Leinster. The family were recorded as O’Melaghlin, and after the 17th century, McLoughlin.

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MacLoughlin of Cineál Eoghain
The McLoughlins of Ulster are part of the Northern Uí Néill. They ruled what is now County Tyrone, Derry and Donegal. High Kings of Ireland from this family were -

Domnall Ua Lochlainn, reigned 1083–1121, with opposition.

Muirchertach Mac Lochlainn, reigned 1156-1166.

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In Scotland
The Northern Uí Néill family expanded from Ulster into Argyll, in Scotland, where Middle Irish ‘Mac/Nic Lochlainn’ became Modern Scots Gaelic ‘Mac/Nic Lachlainn’, most commonly spelled ‘MacLachlan in Scots and English.

The names O’Loughlin and McLoughlin in Ireland are of completely different origin. O’Loughlin is derived from the native Gaelic Sept O’Lochlainn that was based in Counties Clare and Limerick. Loughnane is a variant. MacLoughlin is derived from the Mac Lochlainn Sept that was very prominent in Counties Donegal and Derry and who were a branch of the ruling Ui Neill Sept. MacLaughlin is a variant of this name.