Leixlip is a town located in north-east County Kildare, Ireland. It sits at the confluence of the River Liffey and the Rye Water.
Historically, the town's position has defined it as a frontier location. It served as a border between the ancient kingdoms of Leinster and Brega, functioned as an outpost of the Pale, and marks the boundary between County Kildare and County Dublin. Additionally, Leixlip was historically designated as a civil parish within the ancient barony of Salt North.