"Dr. Isaac Newton" was presumably the alias of a mysterious individual who claimed to be a geophysicist studying radiated rocks in Hooterville but got lost during research. In truth, his origins and identity are a complete mystery.
While "lost", he was found by Sam Drucker and Uncle Joe Carson who took him to the Shady Rest Hotel which he surprisingly knew about despite supposedly being lost and ended up staying with the Bradleys. His stay in the hotel brought many strange occurrences and after witnessing the Royal Order of the Camels, he quickly became fearful and paid his bill before mysteriously disappearing from his room. With his sudden arrival and departure, his true identity remained a mystery; all that was known is that he had come to the small isolated town in hopes of "colonizing" it as revealed in his journal which he had left behind soon after he deemed his colonization project a failure after witnessing the "primitive" and odd traditions of the Royal Order of the Camels lodge and deeming them to primitive for his culture.
"Dr. Newton" had knowledge of many things concerning Hooterville, its people and other events, despite claiming never to have visited before and even knew of the fire that occurred in Crabwell Corners before anyone else. He was also capable of mysteriously moving about without making a sound and seemingly disappearing at will. He also had in his possession currency that had not been printed in decades and a mysterious self-operating "camper". These traits along with the strange happenings that occurred in Hooterville after his arrival and the peculiar way in which he disappeared from his hotel room, suggested that he may have been an extra-terrestrial of some kind, which is further noted when one of Floyd Smoot's rockets hit an odd sounding unidentified flying object shortly after "Newton" disappeared.