L
- (County Monaghan) Lemgare
- (County Monaghan) Lemgare Rocks
- (County Monaghan) Lisnagreeve
- (An Cabhán) Ledonigan
- (County Monaghan) Lisgillan
- (County Monaghan) Lattacrom
- (County Monaghan) Laragh
- (County Monaghan) Lisdoonan
- (County Monaghan) Lisgall
- (An Cabhán) Lisagoan
- (County Monaghan) Lisnadarragh
- (County Monaghan) Lisnalong
- (An Cabhán) Latsey
- (An Cabhán) Larah
- (County Donegal) Legnahoory
- (County Donegal) Losset
- (County Monaghan) Listellan
- (County Donegal) Lahan Island
- (County Donegal) Leabgarrow
- (County Donegal) Lag
- (County Donegal) Labbadish
- (An Cabhán) Lisgrea
- (An Cabhán) Lahard
- (County Donegal) Laputa
- (County Donegal) Laconnell
- (An Cabhán) Largan
- (County Donegal) Largy
- (County Monaghan) Latton
- (An Cabhán) Lavey
- (County Donegal) Leatbeg