extremist

extremist
n (usu derog 通常作贬义) person who holds extreme(3) views (esp in politics) （尤指政治上）偏激的人, 极端主义者
    When it comes to talking about patriotism, he's an extremist. 一谈到爱国主义, 他就很偏激.
    [attrib 作定语]
extremist policies 极端主义的政策.

牛津英汉双解词典