On Fibber McGee and Molly, Thompson brought back the Wimple voice in 1941, and essayed a variety of roles, including a boisterous con man with a W. C. Fields voice, originally named Widdicomb Blotto but soon rechristened Horatio K. Boomer; and Nick Depopulis, the Greek restaurant owner.

Thompson also played the title role, an Adolf Hitler take-off, in Avery's Academy Award-nominated short Blitz Wolf.

Around 1943, however, Thompson's thriving career was interrupted when he joined the US Navy during World War II, and all of his radio characters were temporarily dropped.

He returned to Fibber McGee full-time in 1946, however, and also became a semi-regular on Edgar Bergen's radio series as lecturer "Professor" Thompson.

For Walt Disney Studios, Bill Thompson was heard in many shorts and features, often in either dialect parts or a variation of his Wimple/Droopy voice.

His best showcase may well have been in Lady and the Tramp (1955), where he was heard in no fewer than five dialect parts: Jock the Scottish Terrier, Bull the cockney bulldog, Dachsie the German dachshund, Joe the Italian cook, and the Irish policeman in the zoo.

In 1957, Thompson joined the Los Angeles branch of Union Oil as an executive, working in community relations and occasionally reprising his radio characters.

[3] Thompson's final assignment was the voice of Uncle Waldo in The Aristocats, which was released less than a year before his sudden death from septic shock on July 15, 1971, just one week after his 58th birthday.