Walter Breen

Walter Henry Breen Jr. was an American numismatist, writer, and convicted child sex offender. He was known among coin collectors for writing Walter Breen's Complete Encyclopedia of U.S. and Colonial Coins; "Breen numbers", from his encyclopedia, are widely used to attribute varieties of coins. He was also known for activity in the science fiction fan community and for his writings in defense of pederasty as a NAMBLA activist. He was arrested in 1990 for child sex abuse and died in prison three years later.