The Alphabet Kid appeared in "The Day Herry Monster Held Up the Stage," a story in the 1977 Sesame Street book Tales of Sesame Gulch. One of the younger residents of Sesame Gulch, the Alphabet Kid is, well, a kid whose clothing is adorned with the letters of the alphabet. He overhears the grownups in Hooper's General Store gossiping and spreading a rumor that Herry Monster is tied up with the Jinx gang and will hold up the stage.
The Alphabet Kid rushes off to inform the local law, running into Fearless Ernie. He tells his story and persuades him and Sheriff Bert to form a posse. The Alphabet Kid comes along, but to his surprise and awed delight, he finds that Herry Monster does hold up the stage... over his head, saving it and its passengers from collision with a cattle drive. He would never forget that day.