"...I'm a really lazy engine..."
~ Dennis, Thomas' Day Off, ninth season


Dennis is a lazy diesel. He has a twin named Norman.


When Dennis was new to the railway, he tried to take advantage of Thomas. He soon learnt 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 now on.

In The Great Discovery, Dennis and a number of other diesels later waited in the quarry yard to hear if Thomas had been found in the days leading up to the reopening of Great Waterton.


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 is based on No. 11001, a Bulleid diesel built at Ashford Works, England in 1949 and scrapped in 1959. He also carries his basis' number.


Dennis is painted grey with dark grey wheels and roof and red buffer beams.


Television series

Season 9 - Thomas' Day Off


  • The Great Discovery (cameo)
  • Day of the Diesels (dropped)

He also appeared in tenth and twelfth season learning segments.

Magazine stories

  • 2006 - Dizzy Dennis and Justice for James
  • 2007 - Easy for Edward
  • 2011 - Salty's Surprise!
  • 2012 - Bubbling Boiler (cameo)

Dennis also appeared in the magazine stories, Come back, Please!, Diesel Display, Do-Nothing Dennis, and Speedy Dennis.


  • According to a magazine article, he lives at the Sodor Dieselworks with Diesel 10.
  • The fact that Dennis and Norman are twins is thought to be impossible as No. 11001 was the only one of its type built. However, this dilemma has also been shared with Skarloey/Talyllyn and Rheneas/Dolgoch.
Community content is available under CC-BY-SA unless otherwise noted.