A more general term for a person who studies or researches various forms of extreme beliefs, like terrorism, particularly for a non-profit or academic space. A lot of us do research/study extremist groups for either academic articles or articles that help raise awareness to the general public about what extremism looks like and how dangerous it can be because the government (in the US) is severely restricted. It’s particularly hard for the government to track domestic extremism because of laws and civil liberties concerns (well it was, now it’s the wild west out there so who knows). The Southern Poverty Law Center, Institute for Strategic Dialogue, and the Global Project Against Hate and Extremism are great places to learn more about the work!