The presence of an Angelina Jolie, a Bono or a George Clooney has been a feature of charity fundraising drives for decades.
But British academics have found evidence that celebrities don't help raise awareness of charitable causes.
The chief beneficiaries of star-studded attempts to raise the profile of a good cause are the celebrities themselves, according to sociologists, who say the appearance of altruism boosts their popularity.
Two pieces of research say "the ability of celebrity and advocacy to reach people is limited" and that celebrities are "generally ineffective" at encouraging people to care about foreign causes.
Two-thirds of people could not link any celebrity with a list of seven well-known charities and aid organisations, one paper found.