The rob roy is a cocktail consisting primarily of whisky and vermouth, created in 1894 by a bartender at the waldorf astoria in manhattan, new york city. the drink was named in honor of the premiere of rob roy, an operetta by composer reginald de koven and lyricist harry b. smith loosely based upon scottish folk hero rob roy macgregor.a rob roy is similar to a manhattan, but is made exclusively with scotch whisky; the manhattan is traditionally made with rye, and today also commonly made with bourbon or canadian whisky. while this version of a manhattan may have been first dubbed a rob roy in 1894, the manhattan made with scotch whiskey first appears in print ten years earlier in a london...

Source: Wikipedia