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The Williams Sistersimage via?SI Vault
Age: Venus (15), Serena (16)
Brand: Venus (Reebok), Serena (Puma)
At the age of 15, Venus Williams signed a $12 million dollar deal with Reebok, followed by a $40 million dollar contract with the brand four years later. Her younger sister Serena signed with Puma at 16 for a five-year deal that was eventually worth $13 million.