The Ku Klux Klan. Adolf Hitler. Son of Sam. Ayatollah Khomeini. Timothy McVeigh.

Despite their evil, the world's most notorious killers and villainous groups long ago morphed into historically popular though demonic figures for books, movies and TV shows. And now their artifacts are the rage among collectors.

"Terror-related items are becoming strong, perhaps because of [the Islamic State] and a general fear in the public," suggested Bill Panagopulos, president of Maryland-based Alexander Historical Auctions. "Maybe current events are driving people to buy," he said, explaining that sometimes the news or movies about history, such as "Glory," prompt people to collect historical artifacts.

KKK artifacts from New York being auctioned this week.

And it also prompts people to sell, as seen in his July 7-9 online auction. It includes a McVeigh autograph as well as several KKK and Nazi items, including Klan membership certificates, a painting by Hitler and his personal 13-piece set of silverware.

It's not just a U.S. phenomenon. Another top auctioneer in the Netherlands told the Washington Examiner on background that North Korean-related art is flying off the shelves. Even in Germany, there have been eight recent showings of Nazi-related art and non-military art sponsored by the Nazis.

A 13-piece silverware collection of Adolf Hitler is expected to fetch $15,000.

"I think the reason is time. The living past has become history," the auctioneer said. For example, John Wilkes Booth was widely reviled following his murder of Abraham Lincoln. Now his letters sell for tens of thousands of dollars.

A signature of Oklahoma City bomber Timothy McVeigh is up for auction.

Panagopulos sees new collectors gravitating toward more modern material, from 1900 on. His most recent historical item is a prison envelope used by McVeigh just days before was executed in 2001 for the Oklahoma City bombing. He expects it to sell for up to $400.

Confederate Army items are also hot and he's got several letters written by rebel soldiers, and Confederate money, up for auction.

But don't look for a market for items of even more recent evildoers, like the Newtown, Conn., or Charleston, S.C., killers. "There's no historical attraction there, no political statement, they're just killers. And that's the difference," Panagopulos said.

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.