The Washer at the Ford, or the Washerwoman, is a creepy figure from Gaelic lore. She's usually portrayed as a little old lady, washing out bloody clothes on the night before a battle. If you run into the Washer at the Ford on the night before you go to war, you shouldn't expect to make it home. She has already selected you for her own.
The Washer at the Ford is a version of Morrigan or the Badb (pronounced “bive”), a Gaelic goddess who represents raw sexuality and the terror of the battlefield. The Morrigan is often described as a warrior goddess, but this isn't strictly accurate. She doesn't go to war- she is War. In archetypal terms, she's connected with the Valkyrie as a “chooser of the slain,” and she's also closely tied to the stories of the Banshee. In some regions of Ireland, the Banshee was actually called “the Badb.”
The Badb's name or title also connects her with a Gaulish war goddess known as Cathobodua. This is a Celtic name, and in Irish it would be written as “badb-catha”- which was also one of the Morrigan's titles. In other words, contemporary folk tales about the Washer at the Ford are remnants of the ancient Celtic lore about the terrifying and insatiable goddess of War, whose worship goes back to the most ancient times. Or perhaps “worship” would never have been quite the right word. Warriors may not have worshiped Cathobodua so much as tried to placate her by any means possible!