The Babysitter appeared in in the fourth season Dinosaurs episode "Terrible Twos." Having failed to get results from a pediatrician and an animal trainer, the Sinclairs follow Ethyl's suggestion and call in an expert to tame Baby Sinclair.
The Babysitter has experience in expunging evil spirits and battling the forces of darkness. He wears a pacifier as a crucifix to ward off the baby and insists that no dessert be offered until he has eaten his dinner: "The power of rice compels you!" He emphasizes the importance of boundaries and tries reading from "the bedtime book" (Blue Eggs and Toast). As a last resort, the Babysitter invokes a time-out and asks Fran and Earl to lock the door and refrain from opening it, no matter what they hear. The Babysitter falters, however, and is defenestrated by Baby Sinclair.
The character, and that entire portion of the episode, references The Exorcist (1973), with the Babysitter standing in for Father Merrin.