Democracy is messy. People don't agree on methods, financing, solutions, etc., so the practical problems aren't solved very quickly. Some people prefer a dictatorship where one person tells everyone else what to do and how much to pay.
who are some famous democracy leaders?
In what time period? Since you phrased this in the present tense, I assume you want to know the names of democracy leaders who are still alive and active. If so, start with the current leaders of today's democracies.
the time period doesn't matter. I just need to know the names of some famous leaders throughout democracy.
Pericles, Solon, Cleisthenes, Rousseau, Patrick Henry, Benjamin Franklin, George Washington, Thomas Jefferson, John Peter Zenger, Abraham Lincoln, Henry Thoreau, Winston Churchill, Nelson Mandela, Bishop Tutu, Mohandas Gandhi, and the U.S. Presidents and Congresspeople. You could also add the U.S. Supreme Court justices.