I
- (County Donegal) Illancrone
- (County Donegal) Inch
- (County Donegal) Illies
- (County Donegal) Inishnaneill
- (County Donegal) Inishbarnog
- (County Donegal) Inishkeel
- (County Donegal) Inisheane
- (County Donegal) Inishal
- (County Donegal) Inishmeal
- (County Donegal) Inishtrahull
- (County Donegal) Island More
- (County Donegal) Irineragh
- (County Donegal) Imlick
- (An Cabhán) Inishmuck
- (An Cabhán) Inishmore
- (An Cabhán) Inch Island
- (An Cabhán) Inishconnell
- (County Donegal) Inishfree Lower
- (County Donegal) Inver
- (County Donegal) Inishsirrer
- (County Donegal) Inishmeane
- (County Donegal) Inishkeeragh
- (County Donegal) Inishinny
- (County Donegal) Inishinny
- (County Donegal) Inishfree Upper
- (County Donegal) Inishduff
- (County Donegal) Inishdooey
- (County Donegal) Inishbofin
- (County Donegal) Inishbeg
- (County Donegal) Inishcoo