Dennis is considered to be a very lazy Diesel who tries to take advantage of others and depend on them to do his work. Dennis will often create excuses to get out of work, but usually gets caught in his lies, and always says sorry, but whether or not he means it is the question. Dennis works with Iris at the Container yard, She seems to be the only engine to be able to keep him in line.
Dennis is based on No. 11001, a Bulleid diesel built at Ashford Works, England.
- Toby the Brakevan (deleted scene; cameo)
- Thieves And Whistles (cameo)