The Dark Tower Wiki

Patricia the Mono is the female counterpart of Blaine the Mono.

She was blue, had beautiful glass sides according to Bix, and traveled northwest. Blaine fried Patricia's circuits because he was tired of hearing her cry all the time.

The last stop on her train route was Fedic.

A third known Mono ran to End-World close to the Crimson King's Big Combination acording to Lord Malshun in Black House. The full name of the third Mono is never revealed, if it was given a name.