The Pac-Man Ghosts are Easter Egg enemies only found in Wolfenstein 3D levels Episode 3, Floor 10 & Episode 6, Floor 10 and are part of the remake of the first level of Pac-Man; Blinky makes a surprise appearance in E6L10. These Pac-Man Ghosts cannot be killed or stunned with any weapon and they drain your health alarmingly fast by touching you. Even one can kill a completely healthy player in two to three seconds.
In the Mac Family they have a more textured, three-dimensional appearance. One of them is colored green instead of orange. They also share little resemblance to the actual Pac-Man ghosts contrary to the MS-DOS version.
In the PS3 and Xbox 360 ports, the Pac-Man ghosts are replaced by Fake Hitlers, most likely due to copyright issues. (Blinky still appears in E6L10)
A no-win scenario. All you can do is run away from them. Make sure they do not box you in! If you are boxed in, your only option is to run through them while Sprinting and only taking little damage.