King of the merfolk

The King of the Merfolk was a title given to whoever wielded the Trident of Poseidon. As the king, they would have to power to rule over all mermaids and basically control the entire ocean. Jack Sparrow was given the title after freeing the mermaids from the oppresion of Morveren, Aquala and Aquila but he reclined, believing that even as king he wouldn't truely be free. Jack bequethed his rule to Tonra, the purple-tailed merman.