Piggy is a hostile NPC in Lakeview Cabin IV.
Piggy spawns in the slaughterhouse and is the only NPC in there. He appears to be sleeping until any playable character enters the room and moves, wich wakes him up (if you use any of the secret doors in the mansion to enter Piggy's room, he will instantly wake up, meaning you have to get out quick). Once awake, he will leave the slaughterhouse. He ignores all the traps, and avoids trap doors. Instead of opening doors, he saws them down, giving you a warning that he is about to enter the room. It is nearly impossible to complete LVC IV without waking up Piggy as he guards one of your precious gas cans (But, if you get lucky and get a gas canister from the gift secret room, you may aswell ignore the slaughterhouse complitely).
His movement pattern is fixed: once leaving the slaughterhouse, he runs right (chasing and killing any character outside at that time, so be careful). Once he has ran across the outside of the map, he falls into the trap hole (not taking any damage in the process) and breaks down the door to the trap room. If the alarm has been activated prior to this point, and the machete woman is roaming the basement, Piggy will kill her. He then proceeds to leave the basement, destroying any door in his way. Any NPCs outside their idle position (roaming their room) will be killed by Piggy. He then leaves the mansion, and proceeds to run to the right again, falling into the trap and repeating the process.
Piggy is faster than your characters, and has an extremely high amount of health. Attempting to fight Piggy while he is up and chasing you is suicidal, as his chainsaw has farther reach than any melee weapon and kills you in 2 hits. The easiest way to kill Piggy is to lead him into a bear trap and smack him while he is down. Keep in mind, that you dont have enough time to kill him when he is downed by a bear trap, and will stand up and kill you. But, if you have a chainsaw yourself at this point, you have enough time to kill him.