Binky the Space Cat series by Ashley Spires
Binky is a great graphic novel series for young readers. Apart from being downright silly (Binky does fight aliens that are actually bugs) each book includes a lesson in teamwork, perseverance, trust, and the like (not to mention exclamations like Holy Fuzzbutt!). They are short adventures sure to thrill and amuse. The humor is layered so parents will enjoy this alongside their kids.