Hei Hou (ヘイ・ホウ,Hei hō?) is the sub-boss of Mushroom Hill Zone in the game Sonic & Knuckles, as well as its locked-on form, Sonic the Hedgehog 3 & Knuckles. It is fought at the end of the first act of that Zone.
Hei Hou uses an axe to chop down trees, sending the resulting chunks of wood flying towards the player. If Knuckles is the one battling him, he will use a slightly different attack pattern where the wood chunks bounce and his head is used as an attack.
In Sonic Jam for Game.com, this boss is featured as one of the bosses in the Sonic & Knuckles game. It is extremely easy now, because there is only one tree (to the right), and the boss itself is very slow and chops at a rate of about one time every thirty seconds. In addition, the boss was put lower so it could be visible on the screen, making it possible to simply jump at it.
Having infiltrated Angel Island, Hei Hou ambushed Sonic the Hedgehog and Tails as they were making their way through the Mushroom Hill Zone, where it tried to take a swipe at Sonic with its axe, but the hedgehog dodged it. Hei Hou then tried to attack Sonic with its axe again, but Sonic got behind it and delivered a powerful stamp to its back which destroyed the robot.