Zealots (4)
(Other definitions for fanatics that I've seen before include "People with excessive enthusiasm or zeal as for cause" , "They are excessively enthusiastic or devoted" , "They have extreme enthusiasm for something" , "People filled with excessive zeal, sometimes for religion" .)
(Other definitions for fans that I've seen before include "Devotees" , "Supporters" , "They create currents of air" , "Ardent followers" , "Admirers" .)
(Another definition for extremists that I've seen is " Immoderate folk".)