Well, the modern idea of ‘celebrity’ is somewhat antithetical to the Christian ideals. . .
but I presume you mean people like Mother Teresa, the late Pope John Paul II, our current Pope Benedict XVI–basically saints and saintly figures.
If you mean people who are ‘celebrities’ first by virtue of being entertainers, singers, football players and the like, with the fact of them being “Catholic” meaning no more or less than any other factor, like being black, or left-handed, etc., it doesn’t really matter. Plenty of people who identify themselves as Catholic–or Baptist–or atheist for that matter–live wildly oppositionally to the faith they identify themselves with. And for those who do strive to live according to their faith, that usually matters more for them in their lives than what they receive ‘celebrity status’ for. I would think that people like Danny Thomas or the founder of Domino’s pizza (whose name escapes me now) would be more like that–they considered themselves Catholics who happened to be in Danny’s case an entertainer, and in the other, a good Catholic man who happened to build a great pizza business.