Lawyers for Nelson Mandela's foundation have warned commercial companies to stop using the revered leader's name.
Nelson Mandela uses his prison number in his Aids campaign
About 200 firms have sprung up with names like Nelson Mandela Panel Beaters and Nelson Mandela Fine Art, which have no connections with the man.
His famous prison number, 46664, has also been used by companies.
But the Nelson Mandela Foundation is seeking to register exclusive rights to both name and number, for use in its charitable campaigns.
Trademark registration could take up to three years, but in the meantime the foundation has approached the 200-odd companies in South Africa using the Mandela name.
"We have written letters to all of them asking them to drop the Mandela name," Tim Scholtz, chief operating officer of the foundation, told BBC News.
He said it was the bigger companies they were keenest to chase.
"Where a street is called Nelson Mandela Street, and the organisation is called Nelson Mandela Panel Beaters, we're not too worried," he said.
Mr Mandela wants to register not only his own name, but also his clan name "Madiba", his Xhosa name "Rolihlahla", and his prison number.
The number 46664 is the name of Mr Mandela's Aids awareness campaign, and was used to publicise a huge pop concert for the cause in Cape Town last year.
"Since the launch of the 46664 campaign in Cape Town, people, through the popularity of the events, saw a commercial opportunity," Mr Scholtz said.
They included a company minting gold coins with Mr Mandela's image, Investgold ICC, which had registered 46664 as a phone number.
Mr Scholtz said the firm had agreed to give up the number after being approached.
A dispute over whether the minting can continue is still ongoing, however.
A lawyer for the foundation, Don MacRobert, estimates it has lost "hundreds of thousands of dollars" in potential revenues from Mr Mandela's name and image.