Companies come and go. Part of the genius of capitalism is people get to make good decisions or bad decisions, and they get to pay the consequences... -- on why he didn't help Enron
Paul H. O'Neill became the 72nd U.S. Secretary of the Treasury when he assumed office with President George W. Bush on January 20, 2000. He was born in St. Louis, Missouri, on December 4, 1935. He received a bachelor's degree in Economics from Fresno State College in California, and a master's degree in Public Administration from Indiana University.

O'Neill was chairman and CEO of Alcoa from 1987 to 1999, retiring in 2000. Prior to joining Alcoa, O'Neill was president of International Paper Company from 1985 to 1987, he was vice president there from 1977 to 1985. He joined the U.S. Office of Management and Budget in 1967, serving as deputy director from 1974 to 1977.

The Center for Responsive Politics has this brief bio:

As CEO and chairman of Alcoa, the world's largest aluminum manufacturer, Paul O'Neill decided to dissolve his company's PAC in 1996. "What's going on with campaign financing has reached well beyond a reasonable limit," he told Fortune magazine. "Some people said we'd have a problem with access to elected officials. That hasn't been the case." That's probably because Alcoa relies on Vinson & Elkins, a Texas-based law firm, to lobby the government on its behalf. While Bush was still governor of Texas, Vinson & Elkins got a loophole in the state's environmental regulations that will allow Alcoa to continue emitting 60,000 tons of sulfur dioxide annually into the air, solidifying Alcoa's position as one of Texas' top polluters. Vinson & Elkins was George Bush's No. 3 campaign contributor, giving him more than $200,000. Before joining Alcoa, O'Neill was the president of International Paper. He has also served on the boards of Lucent Technologies and Eastman Kodak.
O'Neill supported the elimination of taxes on corporations, and called for the abolition of Social Security and Medicare. The United States spends one-tenth of one-percent on foreign aid - a far lower percentage than any other developed nation, yet O'Neill believes this was still too much and considered it mostly wasted money.

On December 6, 2002 President George W. Bush asked for and received Paul O'Neill's resignation. Making O'Neill the first of Dubya's cabinet secretaries to be axed - but O'Neill would not go quietly into the night.

In January 2004, O'Neill dropped a bombshell on the President when The Price of Loyalty: George W. Bush, the White House, and the Education of Paul O'Neill by Ron Susskind was released. O'Neill gave author Susskind an unflattering picture of a President disengaged and uninterested in policy - making decisions simply on ideological and political grounds.

In the 23 months I was there I never saw anything that I would characterize as evidence of weapons of mass destruction.
Among O'Neill's assertions in the book was that President Bush began seeking a pretext for war with Iraq in his very first days in office, that there was no hard evidence for Iraq's alleged weapons of mass destruction, and that the President made claims about his proposed tax cuts that he knew were untrue.

I can't imagine I would be attacked for telling the truth. - Paul O'Neill following the publication of The Price of Loyalty
If the book was about the political education of Secretary O'Neill, then the firestorm that surrounded him in the aftermath of the book's release might be called, "The Continuing Education of Paul O'Neill." The Whitehouse immediately unleashed its attack dogs on the scent of Mr O'Neill. Following an interview on 60 Minutes, the administration went so far as to insinuate that the former Treasury Secretary had leaked 'SECRET' documents to author Susskind - even though the document in question had already been obtained by Judicial Watch through the FOIA and was posted on Judicial Watch's website nearly one year earlier.