extremist
n. countablen. someone who has very strong and sometimes dangerous political or religious beliefs. They usually do not accept any middle ground or different opinions.
n. a person who holds extreme or fanatical political or religious views, especially one who advocates for or resorts to uncompromising action. Often used in a pejorative sense to describe those operating outside the political mainstream.
The government is worried about the rise of extremists.
Security forces monitored the extremist group to prevent any potential threats to public safety during the election.
Political analysts argue that the rhetoric used by the extremist faction effectively polarises the electorate, making bipartisan cooperation nearly impossible in the current legislative climate.
From extreme + -ist.
Often used as a modifier before another noun, such as 'extremist views' or 'extremist groups'.