Puma and Adidas
Bear with us: This is an actual sibling rivalry. The fight goes all the way back to the sibling founders of both companies. In the 1920s, German brothers Adolf and Rudolf Dassler created a shoe company together in their mother’s laundry room. As business boomed, so did the tension between them. WWII officially split them up, and Adolf started Adidas, while Rudolf created Puma.