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.
The research was done by Professor Dan Brockington of the University of Manchester and Professor Spensor Henson of the University of Sussex.
"Our survey found that while awareness of major non-government organisations' brands was high, awareness of celebrity advocates for those brands was low," the professors wrote in their article, published in the International Journal of Cultural Studies.
"Instead it was plain from the focus groups that most people supported the charities because of personal connections in their lives and families which made these causes important.
"The evidence suggests that the ability of celebrity advocacy to reach people is limited."
In separate research, Dr Martin Scott of the University of East Anglia analysed British people's perceptions of developing countries by asking them to record their exposure to information about poor nations.
Celebrity involvement in humanitarian causes was rarely mentioned by the volunteers.
"Overall, the results of this research suggest that celebrities are generally ineffective in cultivating a cosmopolitan engagement with distant suffering," Dr Scott said.