Some of the most important changes in American culture have been driven by people born outside the United States. Immigrants may come as refugees, as workers, or as students. They may come as children or as adults. Once here, many speak out for the rights of others or try to build a better country by working within the government. Some give money to good causes. Others point out problems that need to be fixed. Still others create art and music that gives voice to the downtrodden. Here are 25 immigrants who have made a difference by taking a stand.