According to Wikipedia:
A fundamentalist, "is a person who believes in the strict, literal interpretation of scripture in a religion."
That could cover any religion anywhere in the world but generally its's Protestants in America and Muslims in the Middle East and South Asia, parts of Africa who carry that label. Because they're not only religious fundamentalists, but people who are very political and use their religious fundamentalism as their political philosophy. You have countries in the Middle East like Saudi Arabia which officially is a monarchy, but they're also a theocracy and Islamic theocracy. As well as Iran that is official called the Islamic Republic of Iran. Before America invaded Afghanistan in 2001 because the Afghan Government was harboring terrorists who are partially responsible for the 9/11 attacks, Afghanistan under the Taliban Regime was an Islamic state.
You move to America and we see Christian fundamentalists who are Protestants and tend to be Southern or rural as well as Anglo-Saxon with their ancestors coming over here from England in the 16 1700's. America is obviously a federal republic as a well as a liberal democracy with a strong separation of church and state, but if fundamentalist Evangelicals had their way in America they would create their religious theocracy, at least the fringe wing of the Christian-Right in America and establish a fundamentalist Protestant-Christian Anglo theocracy in America. Where women's place in America would be a lot different and a lot more restrictive. Homosexuality and pornography, would obviously be illegal. Certain types of speech when it comes to entertainment but also how people communicate in America would be illegal. Cursing to use as an example. And the argument for these restrictions would be that God wouldn't approve.
There fundamentalist Islamic terrorist groups like Al-Quada and ISIS in the Middle East and Africa, that are looking to take over territory and countries to establish their own religious theocracy. But there also fundamentalist Protestant terrorist groups like the Ku Klux Klan in America, that commit their racist terrorism in the name of God. As well as non-violent fundamentalist Protestant organizations on the Christian-Right in America that would like to see their religious and cultural values become law in America. Where everybody would be forced to live under those values. The Family Research Council would be an example of that. There was a famous Alabama Senate candidate last year whose governing political philosophy was what he called God's Law. His fundamentalist interpretation of the Bible is Roy Moore's governing political philosophy.
Religious fundamentalism doesn't have any one particular owner. Not one religion or religious faction owns religious fundamentalism. Whether it's the Islamic-Right in the Middle East or the Christian-Right in America, or other religious factions in the world. They're just people who believe so strongly in their religious and cultural values and take the literal text of their religious books so literally and believe in those values so strongly and believe they're so great and right, that everyone else should not only live under those same values, but in some cases when it comes to theocrats believe that people in their communities and country's should be forced to live under the same religious and cultural values.
CSPAN: Professor Molly Worthen- Lectures in History: 20th Century Fundamentalism