Feltus / Felthouse. English origins. Recent arrivals they were in Co. Carlow and Co. Wexford in Southern Leinster.

O Fenelon or O Fenlon - Irish / Ua Fionnallain - fionn / fair. A Sept / Family branch, who had their territory in Co. Westmeath in the south - west of Northern Leinster and were Chiefs of Delvin / Delbna.

O Fennell - Irish / Ua Fionnghaill - fair / valour. A Sept / Family branch, who had their territory in Co. Clare in the north - west of Thomond / Tuaiscert Mhumhain / Northern Munster. Elsewhere it is also confused with O Fennelly.

O Fennell - Irish / Ua Fionnghaill - fair / valour. A Sept / Family branch, who had their territory in Co. Dublin in the north - east of Southern Leinster.

Fennell. English origins. They were in Co. Kilkenny in the south - west of Southern Leinster and in Co. Tipperary in the north - east of Ormond / North Eastern Munster from the 14th Century AD.

O Fennely - Irish / Ua Fionnghalaigh. A Sept / Family branch, who had their territory originally in the Heberian Dal gCais O Kennedy kingdom of Ormond  / Aur Mhumhain / North Eastern Munster in Co. Tipperary in the north - east of the Munster Province and nearby in Co. Kilkenny in the south - west of Southern Leinster. They are now also in Co. Laois and Co. Offaly in the north - west of Southern Leinster.

Fenner - Fionur - Fionnbhar / the place / Irish toponymic. They have been in Co. Kilkenny in the south - west of Southern Leinster since the 14th Century AD and in Co. Dublin in the north - east of Southern Leinster and in Fennerscourt and Fennerstown in the 16th Century AD. Finure and Fennors were used as variants.

O Fennessy - Irish / Ua Fionnghusa - fionn / fair - gus - action / vigour. A Sept / Family branch, who had their territory and were Chiefs in their territory near Cashel in Co. Tipperary in the north - east of Ormond / Aur Mhumhain / North Eastern Munster and nearby in Co. Waterford in the south - east of Munster.

Fenning. English origins. They were in Co. Antrim in the north - east of the Ulster Province. Used also as a variant for Fanning, which see.

O Fergus - Irish / Ua Fearghuis - fear / man - gus / vigour / action. A Medical Sept / Family branch with the Heremonian Ui Cobhthaigh Dal Cuinn Ui Briuin O Malleys who had their territory in Co. Mayo in the mid - west of the Connacht Province. Now known as Ferris in Co. Kerry in the south - west of Iar Mhumhain / Western Munster.

O Fergus - Irish / Ua Fearghuis - fear / man - gus / action / vigour. An Ecclesiastical Sept / Family branch who had their territory in Co. Leitrim in Northern Connacht.

Mac Fergus. A Sept / Family branch, who had their territory in Co. Leitrim in Northern Connacht.

Mac Ferguson. Highland Scottish origins. Gaelic Irish / Mheic Feargusa. They are descended from Fergus the Prince of Galloway who died in 1161 AD and they were in the Ulster Province. Also used as a synonym for Fergus, which see, in Co. Leitrim in Northern Connacht.

O Fernan - Irish / Ua Fearnain. Used as a variant for Heffernan, which see, Irish / Ua hIfearnain or as a variant of Farnion, which see, Irish / Ua Farannain.

O Ferrall. Irian Princes in Co. Longford in the north - west of Northern Leinster. See especially - O Farrell.

Mac Ferran - Irish / Mheic Mhearain - mear / swift. A Sept / Family branch, who had their territory in Co. Roscommon in the east of the Connacht Province in the 16th Century AD. Now found in Co. Antrim and Co. Down in the south - east of the Ulster Province.

O Ferrigan - Irish / Ua Fearagain / fearg - anger, fearagain / manikin. A Sept / Family branch, who had their territory in the Heremonian Ui Cobhthaigh Dal Cuinn Ui Briuin kingdom of Breifne O Reilly in Co. Cavan in Southern Ulster. Now also in Co. Down in the south - east of Ulster and nearby in the north of Co. Louth in the north - east of Northern Leinster.

O Ferris - A Heberian Eoghanacht Sept / Family branch of the O Moriartys, which see, who had their territory in Desmond / Des Mhumhain / Southern Munster. Ancestors - *85.Eoghan "Mor"(Eoghanachta), *84.Ailill "Oluimm" the 1st King of Munster.

Ferris. Highland Scottish origins. Previously Mac Fergus who were a Sept of the Mac Fergusons in the Ulster Province.

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