Joannie Palumbo (portrayed by Hayley Chase) was the enemy of Lilly and Miley before dating Oliver and finding out that she and Lilly have a lot in common. She shortly broke up with Oliver but stayed good friends with Lilly, and soon became Miley's (in a way). She is a vegetarian.
Joannie was Lilly's arch-rival since 2nd grade when Joannie cut the string on Lilly's kite and popped Lilly's balloon. In Cuffs Will Keep Us Together, when Lilly and Joannie are both chosen to be football captains in gym instead of betting a quarter like Lilly wanted, they bet that the winner could give the other a haircut. This scared Lilly and so, instead of choosing Miley, Lilly chose the best players and ended up winning the game, shaving off half of Joannie's hair.
In "Joannie B. Goode," Joannie and Oliver start dating much to the dismay of Lilly and Miley. They all agree to get along for Oliver's sake and Miley and Lilly invite her to a sleepover. They spend most of the evening fighting until Lilly and Joannie realize that they both like hockey. They also find out that they have much more in common. Miley is extremely jealous of their close friendship but Lilly promises that Miley will always be her close friend.
It is said in Joanie B. Goode, Joannie does not like Hannah Montana. But in Hannah Montana to the Principal's Office, When Hannah says Joannie's name, Joannie acts excited that Hannah knows her name. Also when Hannah came up to Sarah and Joannie, Joannie and Sarah screamed. It's possible that Joannie acted like she didn't like Hannah Montana when she secretly did.
In "Joannie B. Goode," Joannie and Oliver start dating after what seems to be love at first sight. He doesn't break up with her even though Lilly and Miley both pressure him to do so. They break up in "Papa's Got a Brand New Friend."