1 to 4 meters
Force Wraiths were nonsentient shadowy creatures created from the dark side by the Force power Create Force Wraith. They would obey their creators every command. The creatures radiated pure evil, giving off emanations of cold and death to those who can sense such things, as if they were walking a Dark Side nexus. Force Wraiths could be ordered to perform specific tasks, as well as being able to be controlled by their creators, providing extensions of their creator's senses wherever they went. Both Merilli and Jedgar knew this power, though they both used it in separate ways.
While Merilli's Force Wraiths were huge, standing nearly four meters tall and resembling nightmare versions of Wookiees that were fearsome and devastating in combat, Jedgar's Wraiths were smaller, insectoid things which were roughly two meters tall. In contrast to Merilli, Jedgar used his as spies or guards and, occasionally, warriors when he needed combat fodder. Additionally, while Merilli commanded her Wraiths, Jedgar often remained in contact with his, and used them as his eyes and ears in far-off locations.
Any beings who had faced Force Wraiths and lived to tell the tale remembered the incident much as a child remembers a bad dream. If there were ever any true monsters in the galaxy, Force Wraiths were them.