Jack-O-Bonnie is the Halloween version of Nightmare Bonnie found exclusively in Five Nights at Freddy's 4: Halloween Edition as the secondary antagonist.
Jack-O-Bonnie is essentially just a reskin of Nightmare Bonnie. The changes made in it involve Jack-O-Bonnie being orange, rather than blue, and having an orange candelight glow out of its body.
He acts exactly the same as Nightmare Bonnie, with only a cosmetic change to him.
His role parallels that of Jack-O-Chica, coming in from the west hall of the house. Unlike Chica, however, upon entering the room to attack, he himself attacks the child. He is also the more frequent attacker out of the two.
The child has to hold the left door shut to prevent him from getting in. If the child flashes the light at him when he is standing right outside the door, he will attack him, and if he turns his back on the door to look at the bed, he will enter the room and attack.
The only way to tell he is at the door is to listen for his breathing. Holding the door will cause him to walk away, being unable to enter.
- Jack-O-Bonnie's changes were made to resemble a Jack-O-Lantern, in honor of Halloween.