There are several Percivals scattered through the Harry Potter series, which might help transform the old-fangled, effete image it has accrued. Actually, the original Percival was the one perfectly pure Knight of the Round Table, a worthy hero. The name was invented in the twelfth century by a poet named Chretien de Troyes, for his ideal knight in the poem "Percevale, a Knight of King Arthur."
Percival is found in other forms of literature as well, including Wilkie Collins's The Woman in White, and Tennyson's "Idylls of the King" contains a section devoted to Sir Percival. Wagner transformed the name to Parsifal for his opera.
Percy, which seems like a nickname for Percival but is really a stand-alone Norman place name, is beginning to attract some favorable attention from cutting-edge namers.