What is "karlsson-on-the-roof"

Karlsson-on-the-Roof ( Swedish: Karlsson på taket) is a fictional character in a series of children's books created by Swedish author Astrid Lindgren. The cartoon adaptation became popular in the USSR with its release in the 1970s. To this day, the adaptations are still celebrated as an integral part of the Russian cartoon industry, with Karlsson being recognised as a national icon, together with Cheburashka and other such characters.

Astrid Lindgren might have borrowed the idea from a similar story about Mr. O'Malley in the comic strip " Barnaby" (1942) by Crockett Johnson.