Emily is a beautiful emerald engine who handles goods and passengers on the Main Line.
When Emily first came to Sodor, she took Annie and Clarabel by mistake, causing Thomas and the other engines to be very cross with her. However, after saving Oliver and Toad from a collision at the crossover, all was forgiven and she was rewarded with two coaches of her very own.
When Emily met James at the Crosby Coaling Plant, she filled in the vain red engine as to Logan's exclusive shunting duties around the coal plant. When James further disparages the little shunter, Emily departs, quite put off by James' rude remarks.
Emily was present during Richard Hatt's suggestion box presentation. She was thrilled at the idea of a permanent station pilot, but after Gordon's refusal to allow Dennis do the job, and Charlie and Whiff's eagerness to do the job, Richard moved on. Emily was also pleased at the idea of banning "Auld Lang Syne," though she didn't mind Donald and Douglas singing it, as long as they sang in tune. Later, when Charlie berated Kevin's lousy slapstick, Emily pointed out that the crane was not trying to be funny, but that he was actually just that clumsy, which intrigued Charlie greatly. Later, when Richard was forced to read the comment about Gordon being a galloping sausage, Emily stormed off, disgusted at the immaturity of some engines.
Emily is a beautiful, cheerful and friendly young tender engine that acts as a sisterly figure to the engines. She has a big heart and loves to look after her friends. On some occasions she also enjoys feeling like she is in charge and appears very bossy to the other engines, which can be a bit problematic. All the same, she is a kind engine who is very concientious of the well-being of others, to the point where she almost always has to be involved.
- Season 2: Young Tucker (cameo), Hibernation (cameo), Blunderbuss (cameo), Swashbuckler (cameo)
- Season 3: Marion Saves the Day (cameo), Logan Leaves his Mark, Culdee Fell (cameo), The Suggestion Box, Penn Pals (cameo), Ice Breaker (cameo), Percy and Asbestos, James Goes On A Streak
- Web Clips: Timothy, Bill, Ben, and Marion - Meet the Characters! (cameo), Percy's Kafka Dream (cameo)