My top five most important people in history:
1) Christ: He changed the way people see religion worldwide. I'm a Christian, so he has special meaning to me, but he's important enough to be at the top for secular reasons.
2) Alexander the Great: He changed the world; without him there are no conquerors spreading ideas as well as tax collectors.
3) Aristotle: Alexander's tutor and the man who separated religion from academics. People still seek his wisdom on how to argue and how to think.
4) Muhammad: He changed religion again. He mixes Alexander and Christ in an intoxicating mix of promises, power, and prayers.
5) Charlemagne: His grandfather stopped Muhammad's followers from taking Europe, but he and his progeny were the glue that held Europe together against the Muslims from without, and the chaotic barbarians from within. Like it or not, Europe became the most important continent; none of Europe's success would hold without the secular and religious alliance of the Holy Roman Empire.
Shi Huang Di
There are more, but those are my top five; don't ask me to rate the others.