Diesel D7101, also known as Bear for the growl he makes, is a kindly diesel engine.
Bear, formerly known by his previous number: D7101, came on loan to Sodor with another diesel: Diesel 199. Diesel 199 was blatantly arrogant and bad-mouthed the steam engines until 7101 and Duck shut him up. The next day, 7101's injector failed while pulling the Limited. Henry, who was already towing 199 and had failed himself while pulling some oil tankers, came to help; 7101 was still able to move by himself with some help from Henry. To the passengers' delight, Flying Scotsman took their train, while Henry helped the 7101 home. The engines persuaded Sir Topham Hatt to let 7101 stay on and nicknamed him "Bear". He liked this nickname, saying it meant he "really belonged".