Carl is a diesel engine that works on Oliver's old Branchline. He disliked steam engines at first, but when borrowed and brought to Sodor, he saw how useful steam engines were.
Carl is based on a British Rail Class 56.
- In the script, Carl was called 'Annon Diesel', due to not having a name at the time of writing.
- The name "Carl" came from the TV Show "The Walking Dead." The idea for the name came from Carl's Voice actor, JD41796 while he and Ilovetrains323 were watching at the time of production.