WASHINGTON — Harry Potter, Elvis and Bugs Bunny share one thing in common: Traditional stamp collectors are not fans.

Some philatelists say the committee that helps the postmaster general pick new stamps is favoring pop celebrities and fictional characters over cultural sites and historical figures, undermining a long tradition.

“‘Harry Potter’ is a perfect example,” Ken Martin, executive director of the American Philatelic Society, a nonprofit stamp-collecting foundation that claims 44,000 members. He, at least, doesn’t approve of the fictional boy wizard or his British creator, J.K. Rowling.

“Why do you honor a British author’s book?” Martin asked. “Wouldn’t it be much more appropriate to honor something that reflects our country’s heritage, not the product of another country?”

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The answer, by all accounts, is money. “Spider-Man” and “Star Wars” stamps vastly outsell those commemorating the Civil War, insects and spiders and Pacific Coast lighthouses.

The cash-strapped U.S. Postal Service released its “Harry Potter” stamps last November in 20-stamp booklets and found another hit.

The stamps display images from some of the eight wildly popular films, including Harry reading his acceptance letter to Hogwarts, the school for young witches and wizards and firing his wand in battle. Magical creatures like Dobby the house elf and Hedwig the owl are also featured.

The postal service issued its latest limited-edition commemorative stamp on Aug. 8. It honors legendary blues rocker Janis Joplin, the hard-drinking lead singer of Big Brother and the Holding Company who died at 27.

Postal officials make no apologies for embracing pop culture given its snail-mail image in the digital age. It especially hopes to lure young people into collecting stamps.

“We need to change and improve to serve the changing needs of the American public,” said Toni DeLancey, a postal-service spokeswoman. “Those current Americans that we want interested in stamps, these are probably the images they want to see.”

DeLancey said the Citizens’ Stamp Advisory Committee, a 12-member group appointed by the postmaster general that evaluates future stamp issues based on public submissions, is just keeping up with the times.

But not everyone agrees. Last month, Benjamin Bailar, a prominent stamp collector who served as postmaster general from 1975 to 1978, angrily resigned from the committee after accusing the postal service of “prostituting” its stamps program.

In his letter to Postmaster General Patrick Donahoe, first obtained by Linn’s Stamp News, Bailar suggested the committee be abolished if it is going to recommend cartoons and the like.

“The stamp program should celebrate the things that are great about the United States and serve as a medium to communicate those things to a world-wide audience,” Bailar wrote.

In an interview, Bailer said the stamp program “deserves more than comic strip characters and pop music characters.”