Name: Baron Munsdorf
First Appearance: Action Comics (vol. 1) #31 (Dec. 1940): "In the Grip of Morpheus"
Number of Appearances: 1
Enemy of: Superman
Baron Munsdorf is not a typical criminal. He plots to steal the formula for a new sleep gas from Professor Hunter in Brentville. He does this not purely for money or personal gain, but for his country. The Baron is indeed a villain, willing to steal and kill people to achieve his objectives, but he is not randomly violent. His plot originally involves only putting the people of Brentville to sleep with Professor Hunter's gas. Although this does endanger some citizens, it does not appear that the Baron intended to harm civilians. When Baron Munsdorf does commit murder in this story, it is when he kills his two accomplices, a henchman named Kolb and another unnamed thug. Munsdorf kills these two men for letting Professor Hunter escape before they could coerce the scientist to hand over the formula for the gas. This is an evil, murderous act on Munsdorf's part. But one could make a case that Kolb and the other henchmen were themselves criminals, and weren't really innocent "civilians."
If the Baron had been successful in obtaining the formula for Professor Hunter's powerful sleep gas, he no doubt would have turned it over to his country (located in Europe, but otherwise unidentified) for the purpose of warfare. Baron Munsdorf may indeed be an enemy of the United States. He is indeed a villain. But he is not a purely materialistic, self-serving or "non-religious" villain. He is clearly a man of wealth and means already. He does not engage in this operation for himself, but out of a sincere (if misguided) belief in the cause of his country.
His German name and the fact that he is a baron contribute to the likelihood that this character is a Nazi German "Fifth Columnist." Just prior to World War II there were many stories about Nazi fifth columnists who worked inside the United States to further Germany's Nazi agenda and undermine the United States. It is not surprising that this story never identifies Munsdorf as a "Nazi" by name. Comic books and other forms of popular media created at this time, especially those written by Jewish writers, were particularly hesitant to mention Nazism or Adolph Hitler by name. So, although Baron Munsdorf is not explicitly identified as a Nazi, this is probably what writer Jerry Siegel intended him to be.
Furthermore, Baron Munsdorf's aristocratic status, along with his bearing, speech, and manner, all suggest that his criminal U.S.-based efforts to help his country were borne of sincere belief (or fanaticism) in the Nazi cause. This was not simply a commoner conscripted into an army. Baron Munsdorf was probably a true believer in Nazism.
Just a month or two after "In the Grip of Morpheus" was published, another Superman story was published which focused entirely on Nazi Fifth Columnists. The story, titled "The Fifth Column," was published in Superman #8 (Jan.-Feb. 1941). The terms "Fifth Column" and "Fifth Columnists" were used throughout that story, and it was very obvious that the characters were Nazis. One of the leaders was even drawn to look like Adolph Hitler, complete with a "Sieg Heil" salute in panel 5 on page 3. But the word "Nazi" was still not used, Adolph Hitler was still not mentioned by name, and Germany was not mentioned explicitly.
So "In the Grip of Morpheus" can be seen an early precursor of later stories in which Nazis were recurring villains in Superman stories. Prior to Baron Munsdorf and his henchman Kolb, some earlier Superman villains may have been inspired in part by Nazis and Fifth Columnists, but these two are the first Superman characters identifiable as actual Nazis.