Stephen Blumberg holds the Guinness World Record as the most prolific book thief, having stolen over 23,600 rare books from 268 libraries in North America from the 1970s to the 1990s. His obsession with rare books led him to believe he was rescuing them from neglect, as he distrusted librarians and modern institutions. Blumberg's elaborate heists involved meticulous planning, including daytime reconnaissance using forged credentials and nighttime thefts with stolen keys. His activities went largely unnoticed until a former accomplice, Kenneth Rhodes, informed the FBI, leading to Blumberg's conviction in July 1991. Diagnosed with schizoid personality disorder at age 15, Blumberg lived a nomadic lifestyle, supported by a trust fund and income from selling architectural salvage. His case is notably compared to Guglielmo Libri, a 19th-century thief, though Blumberg's collection was entirely illicitly acquired, making his record particularly remarkable.