Taking office after a 5-4 Supreme Court decision settled the 2000 presidential election, he led America's response to the terror attacks of Sept. 11, 2001, and ordered the invasion of Iraq in 2003 -- engaging the United States in its longest war since Vietnam.
15. Sam Walton, retailing pioneer
A farm boy from Oklahoma who started his retailing empire with Walton's Five and Dime in Bentonville, Ark., he relied on high-volume and low markups to build the world's biggest retailer -- and swamp the competition.
16. Deng Xiaoping, Chinese leader
The de facto leader of China from 1978 into the 1990s, he opened the nation to global markets and economic modernization through "socialism with Chinese characteristics" -- and cracked down on Tiananmen Square protesters in 1989.
17. Michael Jordan, basketball star
Arguably the greatest basketball player of all time, mostly for the Chicago Bulls, his athletic leaps and slam dunks influenced a generation of players. With a likeable persona, he also led all leagues in lucrative endorsements.
18. Howard Schultz, Starbucks entrepreneur
A poor kid from Brooklyn who wanted to replicate Italian espresso bars, he cultivated a chain of coffeehouses that have influenced many Americans' daily habits and tastebuds much as Ray Kroc's McDonalds did a generation earlier.
19. Nelson Mandela, anti-apartheid leader
Released in 1990 after 27 years in prison, he preached reconciliation and was the first elected president of a fully democratic South Africa.
20. J.K. Rowling, author
Her first Harry Potter book, completed in 1995 and initially rejected by several publishing houses, launched a seven-volume series that absorbed children and adults in complicated fantasies spanning thousands of pages.
21. & 22. Bill & Hillary Clinton, 42nd president & N.Y. senator
He was the first Democrat elected to two terms in the White House since Franklin Delano Roosevelt, then survived impeachment. She went from wronged wife to New York senator to the most viable female presidential contender in U.S. history.
23. Russell Simmons, hip-hop pioneer
He helped popularize a distinctively American form of music -- co-founding the hip-hop label Def Jam -- that has influenced mainstream pop culture, from music to dance to dress, since the mid-1980s.
24. Ryan White, the face of AIDS
The 13-year-old hemophiliac from Kokomo, Ind., was diagnosed with AIDS in 1984, then banned from attending his public middle school. A human face for a stigmatized disease, he died in 1990.
25. Homer Simpson, Everyman
The doughy star of the animated TV series "The Simpsons" epitomized the irony and irreverence at the core of American humor -- the same force that helped make "The Daily Show's" Jon Stewart a major source of news for young people.