The Labyrinth Zone boss is the fourth boss in the original 16-bit version of Sonic the Hedgehog, that the player will encounter in the end of Labyrinth Zone Act 3. A similar boss encounter is later seen in Sonic the Hedgehog 4: Episode I, where it is featured at the Lost Labyrinth Zone. In both games, the Egg Mobile is piloted by Dr. Ivo Robotnik.