Halliburton Co. CEO and President Jeff Miller has assumed the role of board chairman with the retirement of Dave Lesar. Miller joined Halliburton in 1997 and served as COO from 2012 to 2014. He became president and joined the board in 2014. Lesar, who joined the Houston-based oilfield services giant in 1993, retired as CEO in 2017 but remained executive chairman. Lesar had served as chairman and CEO since 2000 when predecessor Dick Cheney was nominated as U.S. vice president.