max·i·mal·ist 
(măksə-mə-lĭst)
(măksə-mə-lĭst)n.
One who advocates extremist views or radical action to secure a social or political goal.
[Russian maksimalist, name applied in 1906 to an extreme splinter group of the Russian Socialist Revolutionary Party, ultimately from Latin maximum, maximum; see MAXIMUM.]
maxi·mal·ist adj.