Transformation

Hayden Panettiere had to do some daring stunts during her superhero cheerleader days on Heroes. The 22-year-old is just as fearless offscreen, only her bold moves involve scissors and dye instead of guns and knives. She's gone from long auburn waves to an angled bright-blond pixie in the space of a single year. Why go to such extremes? As she told InStyle, "I've learned that it doesn't kill anyone to put a little work into your appearance." Considering her TV track record, that's a bit of a relief to hear.

The 9-year-old Hayden made her debut in animated film as the voice of Dot in A Bug's Life.