Dennis is a lazy, grey, diesel shunter. He has a twin named Norman.
Thomas & Friends
When Dennis was new to the railway, he tried to take advantage of Thomas by getting him to do all his work for him. He soon learned his lesson when he reversed into a ditch. With Thomas' help, he was able to finish his work and promised to be a Really Useful Engine from then on.
Dennis is considered to be a very lazy diesel who tries to take advantage of others and depend on them to do his work instead. Dennis will often create excuses to get out of work and is infamous for the fact that, unlike most of the engines on Sodor, he does not make an effort on being really useful, and slacks off on a regular basis. As a result of his laziness, he is very unpopular with other engines, but they are forgiving enough to let him redeem himself, depending on how motivated he really is. He usually gets caught in his lies and always says sorry - but whether or not he means it is the question.
Dennis is based on British Rail (BR) 11001, a prototype Bulleid diesel built at Ashford Works, England in 1949 and scrapped in 1959. He also carries his basis' number. Dennis' twin, Norman, is also based on BR 11001.
Dennis is painted two-tone grey with dark grey wheels, gearboxes, roof, and front. His number 11001 is painted on his sides in white, and his jackshaft is red.
- According to a magazine article, Dennis lives at Vicarstown Dieselworks with Diesel 10, possibly an idea from the early stages of production for Day of the Diesels.
- Dennis was originally intended to return in Day of the Diesels, however, he was later dropped and replaced by Norman, who is also based on the same engine as Dennis and is known as his twin.
- Dennis' horn sound comes from a stock sound effects pack and as such can be found in many other pieces of media. It was also mistakenly reused for 'Arry in the eleventh series episode Hide and Peep.
- Dennis, along with Colin, Flora and Hank are the only characters introduced in the HiT Entertainment model era to not have a Capsule Plarail toy.
- Dennis had a total of six facial expressions, one of which (a drowsy face) was never shown on-screen.
- A character face checklist from the tenth series reveals that Dennis was originally going to be named Denzel.