Willa Jean Kemp (born c. 2005) is the name of an obnoxious toddler living on Klickitat Street.
As a toddler, Willa Jean has a tricycle and a water gun. When Willa Jean first appeared in Beezus and Ramona, she was a small 1 year year old girl who Beezus described as "at that weird age" where she was too big for diapers but too little to have a party (Ramona had thrown a fake 5th birthday party for herself, to copy the fact that Beezus was really turning 10). In Ramona The Pest, Ramona seems to find Willa Jean as an interesting 2 year old who, "Isn't a clean little lady". In Ramona Quimby, Age 8, Willa Jean seems to have a best friend named Bruce who she describes as "doesn't wee-wee in the sandbox". Also in Ramona Forever it is revealed she can dial a phone, and is described by neighbors as "Preschool School Girl"