As established with Flash Gordon, Lucas was a big fan of the serials of the 1930s, and it seems that wasn't the only one that he drew inspiration from for his movies. Indeed the most iconic looking figure from the entire series, Darth Vader, appears to have been influenced by a character from The Fighting Devil Dogs. The Lightning, who was the very first costumed supervillain, wore a black leather outfit, complete with helmet and cape. Sounds a lot like a certain Sith Lord. Furthermore, he would fly a spaceship, and had an army who were clad all in white. So while the serial may not be very well known, it can at least lay claim to (probably) having inspired the most iconic movie villain of all time.