This is Mr. Anonymous or as his name is, he is the Dreadster. He clearly was originally a music box named Barry that became sentient after his creator put a drop of blood on his main gear. He was friends with his creator untill he decided it was time to be mature. He was left in the basement in a trashcan untill he got out and made parts to be his current self. After his creator came back from a successfull run at Indigo Park (You should've realized it was Mr. Isaac Indigo thar created Barry,) he was brutally slaughtered by Barry (now known as The Dreadster) numerous times using his tail and then had hidden in the vents when he heard Mrs. Indigo coming to the basement. He clearly made the park close by killing Rambley and eating his heart and making him into a corpse puppet and brainwashing his friends (Except Salem) so he can be able to use them to kill anyone who tresspasses and clearly, he is Salem and Ed's main enemy. (Had to post early because I am PANICKING!!!!!!)
Character belongs to me with permission of @lsikes-tcsral. Indigo Park belongs to Uniquegeese. Songs are by their original creators.