Marcus Sheridan Marcus Sheridan, founder of The Sales Lion, teaches small businesses marketers how to succeed with meaningful content. He is also the CEO of River Pools & Spas, one of the largest pool installers in the country and currently is the most visited swimming pool website in the world, which he has grown using inbound and content marketing methods. Known for his contagious enthusiasm and boundless energy, Marcus has become a popular speaker at such events as Content Marketing World.