|Played by||Robert Jennings|
|First Appearance||Grapefruit's Revenge|
Grapefruit's Sister was a character and a member of Grapefruit's Family. She was Grapefruit's sister and the main antagonist of the episode Grapefruit's Revenge. She came to avenge her brother's death. Grapefruit's sister planned to kill Orange because she heard from a grape named Janey that Orange killed her brother, Grapefruit. Orange, Pear, and Passion Fruit managed to convince her it wasn't Orange, with Orange nicknaming her Chubby McChubby Clown along the way. She started to break down as she didn't know who killed her brother and she came all the way there for nothing. Orange then told her it was Knife that killed Grapefruit. Grapefruit's sister was then gruesomely knifed just like her brother and taken away while Orange, Passion, (and especially Pear, who had feelings for her), watched in horror.
- Her insides were not seen scooped out with a spoon like Grapefruit's.
- She is the first female to be voiced by a male (Robert Jennings).
- She closely resembles Ms. Pac-Man, hence the reason why Orange called her that when he first saw her.
- Grapefruit's Sister is the first female character to die in the Annoying Orange series.
- Grapefruit's Sister is the second character to wear makeup.
- She was rumored to be Grapefruit in disguise, although it is proven false because Grapefruit had died before and came back to life as the head of Frankenfruit.
- She was the second grapefruit character who had been killed.
- She is possibly the mother of Grapefruit's Nephew.
- She is the second female fruit after Passion Fruit.
- She is the second grapefruit character to appear in the series.
- Her kniving looks very similar to Grapefruit's.
- In the episode Googalexiri!, Grapefruit was painting a picture of her, however, she is described as his Mother for some reason.