I got these on the back of postcards sent by Bryon (the USA). I wish they had existed when the Mail Monsters Project was alive!
These monsters are the creation of Canadian author and illustrator Elise Gravel. The stamps were issued on 24 September 2021. In the pane margin area surrounding the 20 stamps are small printed hearts, hats, flowers, word balloons and thought bubbles that can be applied to the stamp when it is used to frank a card or letter for mailing. (More information about this issue)
Go to Sunday Stamps for scarier stamps!