Mark Nielsen (born August 25, 1964) is an American business executive, former elected official, and attorney. Nielsen's current position is Chief Legal and Regulatory Officer of Frontier Communications Corporation (NASDAQ: FYBR), at the company's headquarters in Norwalk, Connecticut. Frontier is America's fourth largest landline telecom company providing data and voice services in 25 states. Nielsen started his legal career in 1990 as an associate lawyer at the Hartford law firm of Murtha, Cullina, Richter & Pinney, concentrating on federal and state litigation.