Black Panther appeared before the Black Panther Party

Marvel introduced King T'Challa as the Black Panther in Fantastic Four #52, published in July 1966. This was actually a few months before the founding of the Black Panther Party in October of that same year. Marvel briefly tried changing his name to 'Black Leopard' to avoid political heat, but both the creators and fans hated it, so they changed it back.