There is no definitive answer to this question, as the identity of Mr. Plaster is a mystery. However, there are some theories about who he might be.
Some believe that Mr. Plaster is a time-traveling individual who uses his knowledge of the future to help people in the present. Others believe that he is a figment of people's imagination, created to help them deal with difficult situations.
Whoever he is, Mr. Plaster has helped many people through his advice column in the New York Times. He has also been the subject of numerous books, articles and even a documentary film.
Despite his popularity, Mr. Plaster remains an enigma. His true identity is unknown and may forever remain a mystery.