Acrophobia

Acrophobia (from the Greek: ἄκρον, ákron, meaning "peak, summit, edge" and φόβος, phóbos, "fear") is an extreme or irrational fear of heights, especially when one is not particularly high up. It belongs to a category of specific phobias, called space and motion discomfort that share both similar etiology and options for treatment.

Mainstream Smurfs Media
In the cartoon show, Hefty developed a fear of heights when he was practicing a tightrope act for a circus that was to be held in the Smurf Village to entertain Baby Smurf.