Charlotte surrounded by guard dog fiends.
Vendetta makes the fiends through a process similar to baking, mixing together ingredients to form them. Vendetta seems to be the only one in Clamburg who knows how to make fiends, although in one episode Charlotte was able to make a friendly fiend without help from Vendetta. (Vendetta only gave her the ingredients.)
Vendetta gets her fiend recipes from a large green cookbook. The base ingredient is a colorless powder, or liquid, called fiend mix. Through Vendetta has been shown in episodes such as "Puppies! Puppies! Puppies!" to be able to make simple fiends from only fiend mix, more complicated ingredients are needed to make fiends with more potential. Another interesting point is that adding any ingredient that doesn't fit can make the fiend come out entirely wrong, as shown in the promo clip "Ralph" and in the segment "Parentnapped".
There are many fiends that take prominent roles in the show (see characters), but many fiends are only shown in one or two episodes before disappearing forever. Many fiends were taken from the online series, such as in the episode "Marvin the Middle Manager"; the "library fiends" were previously "noise-making fiends" shown in web episode 16.
Charlotte can manipulate fiends very easily. It has been shown in many episodes that giving fiends sugar of any kind, or sometimes even just showing them affection, can make them turn benevolent. It is unknown whether this is a flaw present in all fiends, a mistake Vendetta repeats by accident, or some unspoken power of Charlotte's.
Most fiends Vendetta creates only have one purpose, and seem only capable of doing one thing. It is unknown if it is just because a lack of intelligence, if Vendetta only surrounds them with one thing to do, or if it is in the ingredients. Grudge, however, is a more complicated fiend who does anything Vendetta asks.
Fiends by episode
Fiends that Vendetta is not seen to make are listed as "Unknown; probably Vendetta".
TV series
| Episode | Picture | Name | Task | Creator |
| "Charlotte's First Day" | Tentacle fiend | Eat Charlotte. | Vendetta | |
| "A Fiendish Friend" | Buttons 2 | Cut Charlotte. | ||
| "Super Evil" | Mr. Huggles | Hug everyone. | Charlotte | |
| "Vegetables" | Vegetable fiends | Annoy Charlotte. | Vendetta | |
| "Toupee" | Toupee fiend | Make Mr. Milk's wishes to come true, in exchange; Charlotte's destruction. | ||
| "Mama Vendetta" | Exploding pigeon fiends | Explode Charlotte. | ||
| "Shrinking Charlotte" | Shrinking slug fiend | Shrink Charlotte. | ||
| Gianting squid fiends | Make Vendetta big again. | |||
| "Parents" | Mom and dad fiends | Substitute parents for Charlotte. | ||
| "No Singing" | Crush fiend | Crush Charlotte if she sings. | ||
| "Puppies! Puppies! Puppies!" | Guard dog fiends | Keep Charlotte away from Vendetta. | ||
| "Dear Pretty Diary, Dear Stupid Journal" | Book fiend | Vendetta's journal. | Unknown; probably Vendetta | |
| Fuzzy ball fiends | Unknown | |||
| Unfinished fiend | Vendetta | |||
| "Marvin the Middle Manager" | Fiend named Rick | Make students scream.<br>Serve Marvin his chocolate. | Unknown; probably Vendetta | |
| Unnamed fiend | Unknown | |||
| Library fiends | Eat books. | |||
| "Parentnapped" | Burly fiend | Unknown; probably steal things. | ||
| "Smash" | Smash | Smash Charlotte. | Vendetta | |
| "New Best Friend" | Fiend with claws | Destroy Charlotte. | Marion | |
| "Tornado" | Tornado fiend | To take Charlotte far away from Clamburg. | Vendetta | |
| "Pony" | John the Pony | Be Charlotte's pony and destroy her. |