- "I'd rather eat a worm than go to your boring party! Of course, I'd rather eat a worm than do most things, but that's beside the point."
- ―Mr. Bumpy telling the Cute Dolls how he feels about their party in "Party Poopers"
Mr. Bumpy is a friendly green monster that is always chock full of energy (as evidenced in the show's theme song). He is carefree and is always on the lookout for adventure. He can accomplish whatever he puts his mind to if he tries hard enough. Although Mr. Bumpy is generally nice to others, he can be rough towards those whom he dislikes. Mr. Bumpy is usually (with a few exceptions) willing to help his friends with any task they might ask of him.
Mr. Bumpy is a short green monster with purple warts covering his skin and has black spikes protruding from his back. He has long skinny limbs, with 4 fingers on each hand and 2 toes on each foot.
He has long green eye stalks like a snail and large saucer like eyes and and red pupils. He has a bulbous green nose covered in warts and big square shaped teeth.
Mr. Bumpy's best friends are Squishington and Molly Coddle. He is often seen with one of the two (or both) and going on an adventure.
Squishington is very loyal to Mr Bumpy and is always willing to help him with his plans (even when it backfires on him). Bumpy is very friendly to Squish and says that they are the "bestest friend" and do anything for him. Even though Mr Bumpy and Squish have very different interest, such as Bumpy is messy and Squish is clean, they are good friends and do everything together. Mr. Bumpy is shown to offend Squishington at times, but the two usually make up at the end of an episode.
Mr Bumpy is generally nice to Molly and enjoy each others company. Because Molly is very kindhearted and friendly Bumpy call her his "favorite gal." Molly is very down to earth while Mr Bumpy is wild and hyper, Molly acts as the straight man to Mr Bumpy's antics. Bumpy sometimes flirts with Molly and gives her nicknames like "doll face", "toots" and "rag baby", but it is often a way of joking and they aren't romantically interested in each other. Molly isn't a girly girl like the Cute Dolls, which is probably why Bumpy likes her.
Destructo is Mr Bumpy's arch nemesis, Bumpy fears Destructo and he chases him whenever he breaks the rules in some way. The two have a strong dislike for each other and Destructo tries to stop Bumpy from causing trouble. But Bumpy doesn't give up and finds a way to over come Destructo authority.
The Closet Monster is Mr Bumpy's other nemesis, the Closet Monster tries to lure Bumpy into his lair with a dirty sock, and then tries to capture Bumpy or eat him. Bumpy has escaped the Closet Monster many times and sometimes attempts to eat one of the Closet Monster's socks.
Mr. Bumpy has a huge appetite for dirty things such as socks and chewed gum and is willing to go to great lengths to get them. He also likes to eat toe nail clippings and other rotten food.
Mr Bumpy has an powerful appetite and often loses control, such as in the episode "Dr Coddle M.D" Bumpy started eating pages from Molly's medical book and devours the rest, and in "The Night of the Living Bread" Bumpy gobbled up all the food that was suppose to be bait for the Living Bread.
Mr Bumpy is also prone to greed, as shown by his catch phase "Gotta Have It". If he sees sometime or there is something he desires he loses control and is refuses to give up. For example, in "All You Need is Glove" when a Glove takes the perfect left foot sock, he goes through the whole episode trying to get the sock back. Sometimes Mr Bumpy over comes his greed and see's how selfish he has been acting.
Mr Bumpy wanted Santa Claus's bag of toys for himself in the Christmas special T'was the Night Before Bumpy he then loses the presents when the children of the world and the characters and the earthworm Juaquin Gusanito Sin Maños and the humming bird Doris D. Bird get there presents and are happy expect Bumpy who is disappointed and wanted to keep one present for himself and he tells Squishy he lost his feet and Squishy is upset at Bumpy and loses his trust in him Bumpy is ashamed of himself and is deeply upset, he gives Squish the last Christmas present, hoping that someday Squish would forgive him. Squishington opens the gift which is revealed to be "Noise Maker tap shoes", Squish begins clinking the noise making shoes and starts dancing to the music. The toys gather around Squish and watch his performance, he finishes dancing and the toys all applaud him. Squishington is happy that he finally fulfilled his dream to tap dance and forgives Mr Bumpy, becoming friends again. Bumpy is at first confused that all his friends got what they want, but he didn't get anything. Just then, the Earthworm and Doris both appear in the bedroom, Bumpy is surprised to see that the worm is alive. The Earthworm thanks Bumpy for the mechanical arms, saying he has done plenty of quilting. Doris also thanks Bumpy for the jet-pack, saying that she is eating less now and Bumpy then sees that all his friends are happy with their gifts and realizes that sharing gifts to your friends is more important than getting everything. ,Bumpy then sits down at the piano, and sings a reprise of It's the night before Christmas this time he sings about the lesson he has learned that he doesn't need gifts and "giving away gifts uplifts the people that you love and on Christmas that's good enough for him. All of the characters are moved by Bumpy's song and start clapping and Mr Bumpy learns what Christmas is about.
- Ken Pontac the co-creator of Bump in the night came up with the idea for Mr Bumpy along with Jennie Trias, then-VP of Children’s Programming at ABC, asked Pontac and boyhood pal (and creator) David Bleiman to pitch a stop-motion kids show to boost the Saturday morning bill, For his meeting with Trias, Pontac put together what he calls a “totally clueless pitch book” along with a maquette. The duo had animator Josephine Huang sculpt a mock-up of Mr Bumpy with his head tilted back and mouth wide open, about to eat a sock his default position. Trias’s eye passed right over the book, and locked on the bug-eyed maquette. “When Jennie saw the Mr Bumpy maquette, she fell in love with him and bought the project ‘in the room’, as they say in Hollywood,” he recalls. “She told them to have there people call her people. Suddenly they had to get some people!"
- It is also possible that Mr Bumpy's skin color got inspired by Gumby cause Ken Pontac, the co-creator of Bump in the Night worked as art director for The New Adventures of Gumby, before creating Bump in the Night, So Mr Bumpy could be the green sock eating monster version of Gumby.
- Mr. Bumpy also resembles Bugsy from the New Zealand stop motion animated TV series "Oscar and Friends" which premiered a year after Bump in the Night as he is also green, has eye stalks and even his name is similar as they both have the same first two and last letters.
- The idea of Mr Bumpy's love of disgusting things was probably inspired by the character Oscar The Grouch from "Sesame Street" cause there both green, They love trash and they both love living in filthy places.
- Mr Bumpy also kind of resembles Mike Wazowski from the 2001 Disney and Pixar movie "Monsters Inc" with the green skin and could be possible that Disney and Pixar got inspired by Mr Bumpy's skin color but without the single one eye, horns and claws on fingers and toes
- Mr Bumpy as the star of Bump in the night has appeared appeared on every single Bump in the night Merchandise including figures, Plush toys and Subway figures made of him and his best friends Squishington and Molly Coddle.