Phantom BB (or Phantom Balloon Boy) is a boss in Slender Fortress.
Phantom BB is essentially the same model as BB from the second game, but he lacks eyes and has two white buttons (like in The Office in Five Nights At Freddy's 2). He instead has small, glowing, white irises similar to Springtrap and is missing both his "Balloons!" sign and balloon. His rosy cheeks appear to be colored in deep green. Phantom BB appears to be charred or burnt, possibly foreshadowing the torching of the attraction. If one look closely, one can see a light-brown smear on his cap as well as his shirt.
In Slender Fortress Edit
Phantom BB cannot instakill you but he makes your screen flashing red and makes you blink faster, a few Phantom Animatronics has the only helper that CAN instakill you called, Springtrap.