Deezil Oyl is Olive Oyl's little niece, who first appeared in the Popeye the Sailor episode "Popeye's Junior Headache" (1960). She looks like a miniature version of her aunt and wears a big bow in her hair. She has a bratty demeanor, particularly towards Popeye. In Popeye's Cartoon Club, it is revealed that her father is Castor Oyl, with her mother being Cylinda Oyl.
- "Popeye is finished 'cause I ate the spinach for Popeye the Sailor Man haha!" ("Popeye's Junior Headache")
- "Uncle Popeye, oh, please tell me a bedtime story, will ya please tell?, will ya? will ya? will ya?" ("The Mark of Zero")
- "Good night, Uncle Popeye." ("The Mark of Zero")
- To honor tradition with the Oyl family, her name is a pun, this time on diesel oil.
- Deezil's voice was provided by Mae Questel, who used the same voice for Swee'Pea.