In late 2006, stick-figure comics depicting a character who is bound to fail at everything he does started to appear on 4chan. The Character soon became known as “Epic Fail Guy.” On September 30th, 2006, a thread was posted in which “Epic Fail Guy” found a Guy Fawkes mask similar to the one in the movie V for Vendetta in a garbage bin. From this point onward, many more Epic Fail Guy threads would appear on /b/ depicting him both with and without the Guy Fawkes mask. Exactly why EFG wore the mask is unknown, but Anonymous’s preference for the mask seems to have grown directly from this meme. As time went on, Epic Fail Guy began to appear almost exclusively wearing the mask.
By the time Project Chanology rolled around in January of 2008, Anonymous chose to show up in meatspace wearing the Guy Fawkes masks popularized by V for Vendetta not out of tribute to the movie, but as a way of visually telling Scientology they were an EPIC FAIL.