T heodore "Ted" Leonsis is an American businessman, investor, and professional sports team owner. He is the founder, chairman, and CEO of Monumental Sports & Entertainment, the company that owns a portfolio of sports teams and venues in Washington, D.C. He made his first fortune as a senior executive at the internet pioneer America Online (AOL), where he rose to become the president of several divisions during the company's high-growth years in the 1990s. The success of AOL is the primary source of his wealth.

After leaving AOL, Leonsis has focused on building a sports and entertainment empire. He is the majority owner of the National Hockey League's Washington Capitals (whom he led to a Stanley Cup championship), the National Basketball Association's Washington Wizards, and the Women's National Basketball Association's Washington Mystics. His company also owns the Capital One Arena in Washington, D.C. He is also a co-founder and partner in the venture capital firm Revolution Growth, and a well-known philanthropist in the D.C. area.