Here is a super easy tutorial for a Matilda costume from Roald Dahl's book. You probably have the materials on hand already, but if not they are easy to find, and this costume takes only a few minutes to throw together. All that you need is a blue dress, preferably with half-sleeves or long-sleeves. I had mine from a thrift store sale. I suggest you carry a book or two, or a some other element from the story so that people know what character you are. This costume is very quick, and Matilda is a great literary character from an enjoyable classic. This costume is especially good for those who are looking for a costume at the last minute. Not to mention that it isn't too over-the-top, so you could even wear it to work or school.
Here is an illustration by Quentin Blake from quentinblake.com:
I hope you enjoyed! I have more costumes to share, including another Roald Dahl costume, so I'll post again soon!
-Lauryn