Millie is The Earl's private French narrow gauge engine. She works at Ulfstead Castle, she was introduced in season 14.
Appearances
- Season 13: How Gator Stole Christmas (mentioned; not named)
- Season 14: Millie's Castle Hassle, Freddie at the Ready and Cabless Companions (cameo)
- Season 15: Philip Finds a Friend (does not speak), The Island of Misfit Engines (cameo)
- Season 16: Marion Had a Little Lamb (cameo), Luke Dukes It Out (cameo), Bad News Bear (cameo), Victor and Victoria (cameo), and Throw Topham from the Train (cameo)
- Season 17: Hard to Handel (cameo)
Specials:
- Saving Pirate Ryan (cameo)
