The Dead Town by Dean Koontz

The Dead Town is the fifth novel in Dean Koontz's "Frankenstein", which is the collective title of five novels co-written by Dean Koontz.
The war against humanity is raging. As the small town of Rainbow Falls, Montana, comes under siege, scattered survivors band together to weather the onslaught of the creatures set loose upon the world. As they ready for battle against overwhelming odds, they will learn the full scope of Victor Frankenstein’s nihilistic plan to remake the future—and the terrifying reach of his shadowy, powerful supporters. Now the good will make their last, best stand. In a climax that will shatter every expectation, their destinies and the fate of humanity hang in the balance. Victor Frankenstein, having applied his own research to extending his own mortality, is now known to the world as Victor Helios. To the public, Helios is a philanthropic millionaire and a beneficiary to mankind. In reality, he has experienced much in two hundred years since he created a man from fragments of the corpses of criminals. However, in secret, Helios has become obsessed with overthrowing true humans, which he refers to as "the Old Race," and replacing them with his superior creations. After the failure of his first rebellious monster, he put himself through extensive bodily modifications to extend his life span and increase his physical power. This process has left his physical form scarred and deformed. Helios has acquired wealth and power from selling his knowledge to, among others, Hitler, Stalin, and the People's Republic of China. He respected Hitler and was greatly grieved at the end of World War II... (Summary by Wikipedia)