Fill a pint glass three-fourths full with ice. Add the whiskey, vermouth and bitters if desired; stir until well-chilled, 20-30 seconds. Strain into a coupe or cocktail glass or an ice-filled rocks glass. Garnish with a maraschino cherry.
Editor's Note: You may substitute bourbon for the whiskey if desired. You may also strain the Manhattan into a chilled cocktail glass and serve without additional ice.