The answer to the crossword is GEICO, a five-letter company that is well known for its Woodchuck ads. GEICO is an American auto insurance company that was founded in 1936 and is now the second largest auto insurer in the United States. The company is famous for its advertising campaigns, which feature the Gecko mascot and the Woodchuck character. The Woodchuck ads are some of the most popular and recognizable commercials in the United States.