What are some scary things that begin with the letter O?

Here are some scary things that begin with the letter O:

• ombrophobia (fear of rain)
• ophidiophobia (fear of snakes)
• ornithophobia (fear of birds)
• ossivorous (feeding on bones)
• ozostomia (bad breath)
• oneirodynia (nightmare)
• obsequies (funeral)
• obtenebrate (to cast shadow over)
• obtruncate (to cut head off)
• octopus
• Oscar the Grouch
• Orangutan