Molly is a Yellow Main Line Tender Engine.
- Season 7: Neville the Newcomer, Molly's Folly, The End of the Track and Crane Wars
- Season 8: Runaway at the Runway
- Season 9: Hankenstein (cameo) and Tender Bender
- Season 10: Coal Crisis (cameo), Salty Goes Swimming (cameo) and Tour de Sodor
- Season 11: Fergus' Day Off, Duncan in the Dumps (cameo), Hank and the Hatt St Crossing (cameo), Spencer Goes Too Far (does not speak) and Holly Jolly Molly
- Season 12: Scottish Blues (cameo), The Mavis Matrix (cameo), Gordon's Last Hurrah and Henry's Handcar Havoc
- Season 14: Double-Decker-Wrecker (cameo), Hiro and the Heat Wave (cameo), Dirty 'Arry (cameo) and Hatt Trick (cameo)
- Season 15: Flash Gordon, Polar Express Coming Through! (cameo), and The Island of Misfit Engines
- Season 16: Victor and Victoria and Throw Topham from the Train (cameo)
- Season 17: Dustin the Really Useless Engine (cameo), Big Trouble on the Little Western (cameo), James and the Giant Screech (cameo) and Toby, Or Not Toby
- Season 18: Santa Claws (cameo)
- Claw of the Law (cameo)
Molly is based on a Great Eastern Railway D56 Claud Hamilton.