Unit Corporation announced that Chairman John G. Nikkel is retiring from the Board of Directors effective December 31, 2016. J. Michael Adcock, a current board member, has been elected the new chairman. Mr. Nikkel joined the company as its president, chief operating officer, and a director in 1983. He was elected its chief executive officer in July 2001 and chairman of the board in August 2003. Mr. Nikkel retired as an employee and as the chief executive officer of the company on April 1, 2005, but retained his position as chairman of the board.