I dunno if I was ever scared, even as a kid, of any of the RE creatures. Though, IRL...
1. Giant Wasp (Hate Bees/Wasps/Insects in general and the wasps are the fastest & most aggressive insect mutation I can think of).
2. A tyrant, namely the one from RE1 due to the cold, dead stare he has in his face.
3. Regenerators, mainly for being larger, smarter, practically immortal (in a real life scenario), zombie with stretchy arms.
4. Nemesis. His aggression & determination make him so human, it is freaky.
5. Scissor Tails.
Really my list would be filled with all insect mutations as huge insects would cause me to off myself. I wanted to make my list more interesting though so I only used two insect mutations. In game they are nothing but in real life, I couldn't take it.
1. Iron Maiden (RE4) 2. Executioner (RE5) 3. Axe Man (Outbreak File #2) 4. Bandersnatch (Code Veronica) 5. AND THOSE NASTY LOOKING PLAGAS IN RE4! I don't know the "official" name for them, but they're the ones that bite your head off XD