Elvis Presley and The Beatles have again topped a list of the most-forged signatures for a second time.
Authentication service PSA/DNA said under half of their autographs were genuine.
Fake signatures by American astronaut Neil Armstrong, who rarely signed for fans, rose significantly, put him third.
Former US President John F Kennedy and Michael Jackson were also on this list.
Joe Orlando, president of Newport Beach-based PSA/DNA which compiles the list every other year, said that Armstrong, the first man on the moon, knew the value of his own signature.
Margaret Barrett, director of entertainment and music memorabilia at Heritage Auctions said: “A lot of times people stumble on old signed photographs in grandparents lofts and don’t know they’re forged.”
She also said it was common for children to write to the film studios 50 years ago, so more fake signatures are in the marketplace as a result of secretarial and assistants replying to fan mail instead of the actors themselves.
Official documents and contracts are used as reliable sources to ascertain whether an autograph is genuine or fake and its value can vary, down to the smallest of details including which way the letters slope and content.
Beatles signatures , particularly all four, are somewhat rare. However, autographs from their early years are more common, and therefore less desirable.