He is voiced by Richard Correll.
Steve brought him as ventriloquist dummy but the Winslows never seemed to like him and that Steve was unfunny to be a ventriloquist. When Steve fell asleep in his bedroom, Stevil was suddenly brought to life by a lightening bolt from the opening window and he came alive right in front of Steve. Though the Winslows didn't seem to believe Steve when he told them that the dummy was alive.
Stevil later revealed to Steve that he wanted to go after the Winslows because he doesn't like them. To protect the family, Steve locked him in the trunk. Stevil however escaped and terrorized the Winslows one by one. He stuffs Eddie in the chimney, runs down Richie and 3J with Steve's car before trapping their heads in Steve's bedroom wall (right over his posters of Michael Jordan and Dennis Rodman), has Laura dismembered and in pieces of the kitchen cabinet (though she is amazingly still alive), and finally turns Harriette into a jack-in-the-box. Enraged, Steve decides that Stevil must be stopped and throws him in the refrigerator. However, Stevil broke a hole in the refrigerator and escaped. When Steve followed him into the living room, Carl was the only one that was unharmed. When Steve told him about what happened to the rest of the family, Carl seemingly made fun of Steve but soon it was revealed that Stevil had Carl has his puppet. Stevil explained that he took care of the Winslows so he and Steve could go on the road together, only he'll do the talking and Steve will be the dummy. Steve refused and decided to fight Stevil. He seemingly wins the fight by breaking Stevil up into pieces taking him apart. However much to Steve's shock he resembles himself back together and jumps on the couch to strangle Steve. During the struggle, Steve suddenly wakes up screaming in his bed, revealing that the entire episode was a nightmare.
When Steve refused to go to sleep in fear of reliving the same nightmare he had the year before, he revealed to Laura that he took Stevil apart in pieces and flushed him down the toilet. Steve once again falls asleep, this time on the living room couch and once again has a micro nightmare that has Stevil coming alive out of the toilet. He seemingly appears in front of Steve and tells him that he wants his soul. He then shoots green laser beams from his eyes and into Steve's apparently trying to steal his soul but Steve awakens on the couch after the seemingly nightmare. With horror Steve suddenly realized that Stevil was back. When Steve told Carl about the nightmare the next day. Carl once again shrugged it off and again make fun of Steve about his nightmare.
Carl then goes to sleep in his bedroom, where this time it is he who is having the nightmare about Stevil who now has a sidekick of a dummy that looks like Carl called Carlsbad. Together they wanted both Steve and Carl's souls. Carl and Steve terrified run upstairs in the bedroom with which they used the dresser to block the door. The dummies break through but when the lightning flashes again and the lights go out Steve suddenly disappears and Carl assumes that they captured him. Carl goes downstairs to look for Steve and finds him in a blank coma sitting in the kitchen. The dummies appeared and Stevil talks with Steve's voice. Carlsbad proclaims "one soul down one to go" Carl enraged decides to fight the dummies but just as he is about to rescue to Steve the dummies attack him. Carl throws them both out the window and grabs Steve telling him that they must leave. But Steve yanks away Carl's hand and talks in Stevil's voice saying in a creepy way, "What's the rush?". Carl suddenly realizes that Stevil has possessed Steve's body and Stevil shoots green laser beams in Carl's eyes also trying to take his soul. Carl suddenly wakes up in bed revealing that the episode was his nightmare. He goes downstairs and apologizes to Steve for making fun of his nightmare after telling about his nightmare of Stevil. Carl tells Steve that if he ever has a problem with any of his nightmare he can always come to him for help. The duo leave the living room while Steve was trying to tell Carl all of his nightmares.
Had the series gone on for a 10th season, Stevil would've tried one last time to get Steve's soul and since he and Carlsbad went separate ways after a terrible performance in Vegas. He has a new wife, Laurotten, an evil Laura look-a-like doll that wants to replace Laura as much as Stevil wants to replace Steve.