Rex Banner is a U.S. Treasury officer in Washington, D.C. who was briefly sent to Springfield to uphold Prohibition in Springfield after Bart got drunk in a live news report, which incited several women to force the city government to declare Prohibition. He replaced Clancy Wiggum as Chief of Police and made a main objective to capturing the "Beer Baron", a rum-runner who was actually Homer. He also tried interrogating people in regards to who is supplying rum on the side, but his choice of words for his interrogation (Listen, rummy, I'm gonna say it plain and simple. Where'd you pinch the hooch? Is some blind tiger jerking suds on the side?) left one of his interrogatees, Barney Gumble, confused and could only reply with an unsure "Yes?". Also, despite being more competent than Wiggum, Banner seems to be somewhat corrupt, as he doesn't even mind Fat Tony smuggling heroin after refusing to take any bribes to let Fat Tony smuggle alcohol to Springfield. When Homer was finally turned in by Wiggum, Rex was fired, both from his job as chief, and from the main mechanism of punishment for breaking the ancient prohibition law: catapult. 
Though a very clean cut, non-nonsense officer, he did not seem to be any more effective then Wiggum as police chief. Banner was never able to identify Homer as the "Beer Baron". Even with overwhelming evidence, and Homer's general sloppiness in covering his own tracks.
Behind the Laughter
Rex Banner was based on Eliot Ness, the Treasury agent who led the famous Prohibition-enforcement team "The Untouchables". His voice is based on Robert Stack's portrayal of Ness in the Untouchables TV series. His appearance is based on Kevin Costner's portrayal of Ness in the Untouchables film.
- Episode – "Homer vs. the Eighteenth Amendment"
- – The Simpsons Movie (Cameo)
- Video game – The Simpsons: Tapped Out