Brennan on the Moor
Like Roddy McCorley, Brennan is a dashing hero from County Tipperary, but unlike the martyred Roddy McCorley, he's not political. Highwayman Willy Brennan is a kind of Irish Robin Hood.
In this ballad, after the Mayor of Cashel tries to apprehend him on the road, Brennan gives his wife as secret signal by asking her for a ten penny piece. Instead of a coin, she "hand[s] him a blunderbuss from underneath her cloak."
With this, he holds up the mayor, and repairs to the moor with a price on his head. His later downfall is attributed to "a false-hearted woman" who "cruelly betrayed" him. This leaves questions. Would that traitor be his wife? If so, why does the ballad refer to her as simply "a woman," when she's been mentioned before? Some versions have Brennan killed at the crossroads, then returning as a ghost.
Here's Declan Nerney with the song, and here are the Clancys.