American entrepreneur Karl Eller has an estimated net worth of $400 million in 2012.

It was in 1962 when Eller acquired the Arizona operations of Foster and Kleiser, a billboard advertising company based in New York. Eventually, he developed it into a major business in the region. In 1968, he became one of the founding investors of the National Basketball Association's Phoenix Suns.

On the same year, the merger of KTAR radio and television and Foster and Kleiser took place which led to the forming of Combined Communications, Inc. At its peak, Combined Communications Inc. became the owner of seven major metropolitan television stations,  two metropolitan daily newspapers, two Canadian and 12 American outdoor advertising companies, and 14 major metropolitan radio stations.

Subsequently, he became the head of Columbia Pictures. He also played a crucial role in developing Circle K into the the largest publicly owned convenience store chain as well as second largest convenience store operation in the country with over 4,641 stores in 32 states. When Circle K declared for bankruptcy, Eller immediately resigned from his post in the company.

In March 2004, Karl Eller was inducted by the American Advertising Federation into the Advertising Hall of Fame in New York City, making him the second outdoor advertising executive and first Arizonian to have received such honor.