The talk show host Oprah Winfrey has the Big Give, a televised competition to promote philanthropy by seeing which contestants can make the best gifts. Other celebrities like the rock star Bono are raising money and awareness to help end poverty and hunger in Africa.

But celebrity pitches don’t persuade many Americans to support new causes, according to results of a Harris Poll released today. Only 15 percent of respondents in the survey said they had supported a cause or requested more information about it because of something they heard a celebrity say or do.

What’s more, 51 percent said that celebrities make little or no “positive difference” on the charitable issues they promote.

But celebrity philanthropy fueled by television, film, and other media shows no sign of slowing down.

NBC is planning a one-hour drama next year about a “renegade” billionaire philanthropist who goes to extreme measures, including dodging bullets across the world, to help others in need. Take The Chronicle’s poll now, and tell us who you think should play the philanthropist in the series.