If a single characteristic defines the men and women of this year's Texas Twenty, it's toughness—a willingness to fight for what they believe in, plow through apparently immovable obstacles, and overcome seemingly insurmountable odds to achieve greatness. Think of former assistant U.S. Attorney Bill Johnston, who bucked the Justice Department on the Branch Davidian case at great cost to himself personally and professionally. Or soccer star Mia Hamm, whose poise on the field and off has won her legions of fans and a level of respect that too often is reserved for male athletes. Or Karl Rove, George W. Bush's chief strategist, who guided the governor through the difficult GOP primary season and is now trying to help him win in November. Not all tough Texans are outwardly so, of course. Wayne Isom, the heart surgeon who saved the lives of Larry King, Walter Cronkite, and David Letterman, isn't flashy, but no one doubts the steel at his core. Then there's Rod Paige, the superintendent of the Houston Independent School District. Is there anything that requires more toughness than educating thousands of kids in one of the largest cities in America? He rises to the challenge every day—and that alone makes him worthy of inclusion on our list of the most impressive, intriguing, and influential Texans of 2000.