Gus Winkler (March 28, 1901 – October 9, 1933) was an American gangster who headed a Prohibition-era criminal gang specializing in armed robbery and murder for hire with Fred "Killer" Burke. Winkler was a senior associate of Chicago Outfit boss Al Capone and is considered a suspect in the St. Valentine's Day Massacre. Winkler is believed to be the first member of the National Crime Syndicate to be murdered for talking to the FBI.