Hilary (also spelled with two 'l's) is a hot potato of a name, so closely identified with Sen. Clinton that it's hard for most parents to see it as a baby name. A pity, really, as it's got so much going for it: the popular, rhythmic three-syllable structure, the fact that it's strong but light, proper but jaunty, with an irresistible meaning -- having the same root as hilarious.

The only version that works for boys anymore is the Latinate Hilario or Ilario. Better to look to Felix for a happy-meaning name.