Molly is a large, powerful and bright yellow engine. She is proud of her strength and wants it to be used and useful. As well as being mighty, however, Molly is also sensitive. She's very aware of what the other engines think of her and wants them to think the best.

 

Molly shies away from conflict as she finds it upsetting. On her first day, she was teased for pulling empty wagons. She felt inferior to the other engines, and wanted to feel just as useful as them. However, in the end, Molly saw sense (thanks to Thomas) that even empty wagons can be just as important as loaded ones.

 

Molly is distinct in her colour and styling from any other engine on Sodor.