Prof. Oak is a kind guy who studies Pokémon for a living, including legendary Pokémon.
Professor Oak has many old friends. One of them is Kurt, a Poké Ball smith from Azalea Town, and another is Professor Elm, who used to be Oak's assistant. In fact, there is a picture on Kurt's wall saying "...a young Prof Oak?". His known family are his grandson Gary, his cousin Samson, and his great-grandfather grand Oak. His often-forgetful attitude and other antics are also notorious.