T. Boone Pickens Jr., an oil man and pioneer in hostile takeovers, has died. As the longtime chief executive of (PXD), an independent oil and natural-gas company he founded, Pickens’ folksiness, advocacy for shareholder rights and populist vilification of “Big Oil” helped turn him into one of the most recognizable executives in the U.S. for decades. Born in Holdenville, Okla., Pickens was a trained geologist who went to work for Phillips Petroleum after graduating from college.