Rattleballs

Rattleballs (voiced by Rainn Wilson) is a gumball robot cavalier introduced in the eponymous episode "Rattleballs." He was designed hundreds of years ago by Princess Bubblegum to protect the Candy Kingdom. After Princess Bubblegum kills his fellow Gumball Guards for being too violent, he hides out in a junkyard. When Finn alerts Princess Bubblegum to Rattleballs' continued existence, she tells the Banana Guards she has killed him, but secretly reappoints him "Sir Rattleballs," charging him to protect the Candy Kingdom from the shadows. In "Jake the Brick," he is seen creating more Rattleballs Robots while listening to Jake's bunny story. In "Reboot," Rattleballs appears to be killed by Susan, where she shattered him into pieces, but he is later seen at the Candy Kingdom Hospital in "Do No Harm" where he has been put back together, evident by the various cracks throughout his body. In "Nemesis," he is mentioned by Colonel Candy Corn and Princess Bubblegum, and seen in Finn and Jake's bathtub competing with them on who can hold his breath the longest. In "Jake the Brick," he is seen creating more Rattleballs Robots while listening to Jake's bunny story.