Bully is a whitish-gray rat who appears as an enemy of the Farthing Wood Animals in both the books and the TV series. He is the leader of the rats who attempt to take over White Deer Park in the books and the TV series. In the books, Bully emerges as the leader quite late on, when the rats are struggling to take over White Deer Park due to the attacks by the park's residents. In the TV series, he is shown to already lead the rats as soon as they arrive at the reserve. Bully is the main antagonist of series 3.
Bully is an extremely vicious and threatening character in the books, but in the TV series he is considerably less threatening and more comedic, as well as more caring, affectionate, and sympathetic of his fellow rats (but still very vicious). In the TV series, he has an unusually long tail (even for a rat) which he often waves to alert the other rats and uses it as a whip to attack them and other creatures. He also constantly uses the phrase "Who am I?", to which the other rats typically reply "Bully, Bully, Bully". In the books, he is killed by Vixen during the final battle to take over White Deer Park, but in the TV series he has his tail bitten off by Cleo and retreats with the other rats back to the sewers.