A former hair stylist for Nicki Minaj is suing the star for $30m (£18m), accusing her of selling wigs based on his designs without permission.
Terrence Davidson began working for the rapper in 2010, creating multiple wigs for high-profile events and her Super Bass music video.
Mr Davidson claims he had previously discussed a joint business venture with Minaj to launch a line of wigs.
Representatives for Minaj have yet to comment on the legal action.
Mr Davidson says the star is now copying his wig designs and selling them online.
According to legal papers filed in Atlanta, the hair stylist says he also turned down a contract for a reality TV show on the advice of one of Minaj’s representatives, with the promise of creating his own reality show with the star about being a celebrity wig stylist.
But after months passed in 2012, he claims the rapper and her team “took active steps to isolate [him] and preclude him from the notoriety he deserved for his wig designs”.
Mr Davidson – whose celebrity clients also include singers Patti LaBelle and Jennifer Hudson – stopped working as Minaj’s stylist in early 2013, citing creative differences.
Christopher Chestnut, a lawyer for the hair stylist, said his client’s wigs “significantly contributed” to Minaj’s notoriety and helped her rise to fame.
He said the star “took a number of his popular wig designs, without his consent, and used them to start her own wig line”, resulting in at least $30m in losses.
“Her lawyers may complicate it, but we don’t need to get into intellectual-property law. “This is basic American morality. Nicki Minaj lied to this man and cheated him,” he said.