Marvin Monster is a well-mannered monster who works as a stocker at Mr. and Mrs. Mopple's Market. He appeared in the short story "The Mystery of the Missing Muffins," first published in On My Way with Sesame Street Volume 1. Sherlock Hemlock asks Marvin if he's seen magicians, marbles, mice, and other M words, in his quest for the muffins. However, Marvin himself had astutely located them next to the marmalade, for the convenience of those who desired condiments with their breadstuffs. The case is solved, and Marvin returns to the illustrated shadows from whence he came.