Emily is a large Stirling Single tender engine. She has her own rake of coaches.
In the seventh season, Emily acts as a sisterly figure to the others. Emily is kind and friendly and always sensitive to the other engines' feelings. If she wrongs someone, knowingly or not, she is quick to apologise.
From the eighth season onwards, however, Emily can tend to get into trouble because of her fussy and bossy attitude, but she is nicer than she lets on. She seems to want to strive to be one of the best, and it sometimes causes mishaps, though she usually makes up for her mistakes when she realises her errors.
From the seventeenth season onwards, however, her personality has reverted more to how it was in the seventh season.
Emily is based on a GNR G3 Stirling Single. The only surviving member of her class (No. 1) is on display at the National Railway Museum.
Emily is painted emerald green with gold and yellow lining. She has chocolate running-boards and her buffers were originally bronze but are now silver. For The Great Race, gold trim and flowers were added to her coat for her participation in the Best Decorated Engine Parade.
- Season 100 - Geoffrey's Real (cameo), Toby and Philip (cameo), Henry the Warrior (cameo), Trouble with Brakevans, Coach Brakes (cameo), Jealous James, Salty's Secret Story (cameo), The Crashing Kipper (cameo), The Lost Letters (cameo), Snowploughing at Christmas, Duncan's Dilemma (cameo), and Henry in the Darkness
- Teresa Gallagher (UK; Hero of the Rails onwards)
- Jules de Jongh (US; Hero of the Rails onwards, UK; Thomas and Friends in 4-D: Bubbling Boilers and The Great Race singing voice only)
- Blanche Ravalec (France and French speaking Canada; seventh season onwards)
- Yuka Shioyama (Japan; seventh and eighth seasons)
- Erina Yamazaki (Japan; Calling All Engines! onwards)
- Marit Berg (Norway; Hero of the Rails - seventeenth season)
- Marianne Westby (Norway; Day of the Diesels onwards, excluding the sixteenth and seventeenth season)
- Chiara Gioncardi (Italy)
- Diana Pérez (Latin America; Hero of the Rails onwards)
- Marjolein Algera (The Netherlands)
- Kristina von Weltzien (Germany)
- Judy Winter (Germany; Audio Books only)
- Joanna Pach (Poland; Hero of the Rails onwards)
- Mia Kadosh (Israel)
- Kate Kelly (Brazil)
- María Sánchez (Spain)
- Susa Saukko (Finland)
- Ioana Perneș (Romania)
- Thanh Hống (Vietnam)
- Olga Kuznetsova (Russia)
- Although the second female steam engine to ever appear in the television series (the first being Lady), Emily is the first canon female steam engine in the series as well as the first female steam engine to appear and remain on a regular basis.
- Emily has a Scottish accent in the UK version, reflecting the origin of her designer. But in the US dub, she has an American accent.
- Emily is the first character to be the main female steam engine ever since Emily's New Coaches aired on broadcast.
- One of Emily's models was on display in Canada at Nitrogen Studios, it is now part of the touring Thomas and Friends: Explore the Rails exhibit.
- Emily is the first character besides Thomas himself to say his infamous phrase, "Cinders and Ashes", which was done in Tickled Pink.
- Some literary articles show her being sisterly mostly to Thomas and James: according to a magazine bio, she has a particular fondness for James and treats him like a little brother. In Railway Rhymes, the author states that Emily and Thomas act like brother and sister.
- Emily is the only member of the Steam Team not created by Wilbert Awdry.
- According to Robert Gauld-Galliers's concept art, Emily was originally going to have handrails on top of her smokebox, three front coupling chains and a gold symbol on her wheel arch.
- From the thirteenth to fifteenth seasons, Emily was incorrectly shown as emitting smoke from her safety valve.
- Emily had many modifications throughout the television series. These include:
- Season 8:
- Her buffers changed from bronze to silver.
- She shares the same whistle sound as Henry.
- Season 9:
- Her whistle becomes an pitched-up version of Henry's whistle.
- Season 11:
- Her forward buffer housings' colour changed from black to red.
- Season 12:
- Her face became larger.
- Hero of the Rails:
- Her face became a bit smaller.
- Her whistle is the same as Henry again.
- No Snow For Thomas:
- She received a permanent lamp, a taillamp, a new whistle sound, which is Stephen's at a higher pitch and lampirons.
- Season 19:
- She gains a brake pipe.
- She received more prominent front and rear brake-pipe outlets. Strangely, the ones that have been there since she was introduced have not been removed.
- Her side rods become silver.
- Snow Place Like Home and parts of Best Engine Ever only:
- Her brake pipe faces downwards.
- Season 8: