|“||I'm not mean! -O.R. Wellington!||”|
— Olivia in Underfist: The Horror of Halloween Candy
Olivia R. Wellington  is an straight-A student, nice, smart and pretty girl. Her sister is Xandra. Her brother is Tommy Wellington. Her parents are Genevieve Wellington and Terry Wellington. Her best friend is Gwen Blue. She is voiced by Bridgit Mendler.
Olivia is a kind, intelligent, creative 12 year old kid who cares about her family and friends.
She has light blue eyes and strawberry blonde hair. She wears an teal short sleeve shirt and jeans. She wears brown fuzzy boots.
Although her middle name is not fully reavealed, some people think her middle name is Rae, Radcliff, or Rachel, but it's not.
- She has 4 dogs, 2 cats, and 1 guinea pig.
- Her favorite colors are teal/blue, yellow and pink.
- Her phobia is gum.
- Her horoscope is Capricorn.
- Her Birthday is on January 18, 2000