Biography
So it's been a while since you answered the Call to Adventure, and you've had some successes. Spectacular successes, even. Everyone has heard of what you've done and everyone knows your name. . . but they don't know what you look like, and you don't exactly look the part. Maybe you're the Kid Hero, Little Miss Badass, Cute Bruiser, Pintsized Powerhouse, a Lady of War with a Tomboyish Name, or Really 700 Years Old; it may be the result of a Big Shadow, Little Creature, or maybe you just lack the movie-star looks everyone associates with a heroic role.
Either way, your reputation precedes you, and every time you introduce yourself, people are going to look at you and say "Oh! I was expecting someone taller...". Or worse, they'll ask if you've met/heard of/know of... well... you. Then you have to say Actually, I Am Him. Or even worse, they'll think your associate is you, and then you have to say Actually, That's My Assistant.
Alternatively, maybe you're just a Dirty Coward with an Astonishingly Appropriate Appearance who happened to be in the vicinity of great events.
Can be Truth in Television — research has shown that people make links between people's height and their perceived success, even if they know nothing about them.
May overlap with Shrouded in Myth, where it's the exaggerated reputation or description that causes the disappointment. Can lead into a Warts and All plotline, where they can realize their expectations are wrongheaded.
If someone is simply commenting mockingly on the height of another character with no reference to their reputation, see Acceptable Targets or The Napoleon.
See also Beauty Equals Goodness, Mistaken Age, Recognition Failure, Badass on Paper, Nothing Is Scarier.
Not to be confused with the Tom Holt comic fantasy novel, Expecting Someone Taller (1987).