- Long Island Well
- Longford
- Lough
- Loughlass
- Luggacurren
- Leixlip
- Linns
- Little Ash
- Littlemill
- Lordship
- Louth
- Lurgan
- Lurgangreen
- Lackmelch
- Lady Island
- Ladyrath
- Lamberstown
- Laracor
- Large Island
- Laytown
- Leggagh
- Light Town
- Liscartan
- Littlerath
- Lobinstown
- Loganstown
- Longwood
- Lordstown
- Loughanbran
- Loughanderg