The term 'Sly One' can be defined by the following crossword solutions: Sylvester Stallone (8 letters), Sharpie (7 letters), SNEAK (5 letters), FOX (3 letters), and Leerer (6 letters). Sylvester Stallone is an American actor, director, producer, and screenwriter who is best known for his action roles in films such as Rocky and Rambo. A Sharpie is a permanent marker used for writing on surfaces such as paper, plastic, or metal. To SNEAK means to move quietly and secretly, often with the intention of avoiding detection. A FOX is a small carnivorous mammal that is known for its cunning and sly behavior. To leer means to look at someone in a suggestive or menacing way. All of these words describe someone who is sly and cunning.