Grumbo Share definition Flag A deformed creature who lives with a Jewish family in the 1940s. His family ends up getting captured by Gestapo, and is left all by himself in an attic. Have you seen Grumbo lately? I heard that he's still hiding in the attic. Grumbo by Zephyr321 April 14, 2019 0 0 Get merch Get the Grumbo mug. Buy Now — $32.95 See more merch