Brainy Simpson is a character from the popular animated television series The Simpsons. He is the eldest child of Homer and Marge Simpson and is known for his intelligence and academic achievements. The crossword solutions for Brainy Simpson are LISA (4 letters) and MENSA (5 letters). Lisa is the name of Brainy Simpson's younger sister, while Mensa is an international organization for people with high IQs, which Brainy Simpson is a member of.