Freddlets (also kown as Freddles) are major antagonists of Five Nights at Freddy's 4. They are known as Fredlets or other names by the fan base, and they randomly appear on the child's bed to help them summon Nightmare Freddy to kill the child.
Five Nights at Freddy's 4
The Freddles only appear in Five Nights at Freddy's 4 with a small role. Their job is to summon a nightmare version of Freddy Fazbear to murder the child.
Little is known about them, but it is assumed that they work for Nightmare Freddy. It can also be speculated that they are in some way the same entity as Nightmare Freddy, and simply need to combine in order to turn strong enough to kill the child. They don't appear in mini-games, most likely meaning they have little effect on the story.