1. Tom Beck in Deep Impact (Morgan Freeman). America gets a black president. World ends.
2. David Palmer in "24" (Dennis Haysbert). America gets a black president who spends all of five minutes worrying about civil liberty violations, making him a vast improvement over real president.
3. "Jed" Bartlett in "The West Wing" (Martin Sheen). America gets a Nobel laureate whose policies seem strikingly Clintonian, except that he's a lot more fun to listen to.
4. James Marshall in Air Force One (Harrison Ford). America gets a neocon president who, personally, kicks Russian terrorist ass. (Bonus: fascinating opening sequence in which special ops kidnap evil post-Soviet dictator fools with moral sense.)
5. James Land in Mars Attacks! (Jack Nicholson). America gets Randle Patrick McMurphy. Must have been a lot funnier on paper.
6. Unnamed in The Rock (Stanley Anderson). America gets a nonentity with noname who spends 15 seconds thinking about killing 50 unnarmed civilians in order to save San Francisco.
7. Unnamed, McKenna, and Unnamed in X-Men, X-2, X-Men 3: The Last Stand (David Black, Cotter Smith, Josef Sommer). America gets three nonentity presidents. Makes sense that America would search out bloodness figures with zero screen presence in near future where everyone hates and fears rise of charismatic, sexy mutants who walk around in tight leather.
8. Thomas J. Whitmore in Independence Day (Bill Pullman). America gets uncharismatic dude who can't deliver a halfway decent speech as aliens destroy world. Choice of people calls into question human race's right to exist in the first place.
9. Bill Mitchell in Dave (Kevin Kline). America gets complete dick, eventually saved by likable dude who looks just like complete dick.
10. Andrew Shepherd in The American President (Michael Douglas). America gets....aww, that's sweet. He's rediscovering love as a middle-aged man, meaning that even someone as lowly as the American president can find someone.