Killashee (Irish: Cill na Sí)[2] is a village in County Longford, Ireland.

It is situated on the N63 midway between Lanesborough and Longford, near the Royal Canal and 8 km (5.0 mi) east of the River Shannon.

Killashee has produced some inter-county players through the years.

The closest airport to the Killashee is the Abbeyshrule Aerodrome located 33 kilometres south-east of the village, the closest major airport is Ireland West Airport in Charlestown, County Mayo, 91 kilometres north-west of Killashee.

Route 425 provides a weekday service each way to/from Galway via Lanesboro and Roscommon.