Nightmare Fuel / Animalia

• The Creeper. His mere existence single-handedly increases the show's fear factor up to ridiculous levels.
• In "Goodbye, We Must Be Staying", the citizens of Animalia gradually start reverting back to their wild, uncivilized state, acting like real-life wild animals, with the predatory ones out for fresh meat.
• The giant jungle frogs from "The Mist of Time", which are large enough to swallow a gorilla whole. As if that weren't scary enough, they briefly return in a cameo appearance in the following episode, this time with sharp teeth!
• The giant, glowing eyes in "Don Iguana".
• Those giant wasps from "The Mystery Of The Missing Melba". Not only are they giant wasps but their buzzing sounds very loud and very realistic. Anyone with a phobia of stinging, buzzing insects may want to skip that particular episode.