There are a few descriptions of gentle giants in different literature and movies. Of Mice and Men describes Lenny as a guy who is not a giant, but a large man with the mind of a child, though John Malkovich, the actor who portrays him in the movie, is not a remarkably large guy.
The 7 foot tall guard accused of groping the girl at the gate in the book was usually described as a gentle giant who was impotent, though he became hostile when ordered to do so by his boss.