Is Patrick dempsey and jack dempsey related?

No, Patrick Dempsey and Jack Dempsey are not related. Patrick Dempsey is an American actor best known for his role in the TV series "Grey's Anatomy," while Jack Dempsey was an American professional boxer who held the world heavyweight title in the 1920s. The similarity in their last names is purely coincidental, as they come from different backgrounds and professions.