The eighth season of the television series was the first to be produced by HiT Entertainment. The twenty-six episode season was first broadcast in 2004 and narrated by Michael Angelis in the UK and Michael Brandon in the US.
- Thomas and the Tuba - Thomas looks for the brass band's tuba player.
- Percy's New Whistle - Percy plays pranks with his whistle.
- Thomas to the Rescue - Diesel gives Thomas a hard time at the quarry.
- Henry and the Wishing Tree - Henry learns to be careful what you wish for.
- James Gets a New Coat - James learns that pride comes before a fall.
- Thomas Saves the Day - Thomas tries to tackle a dangerous bend without Annie and Clarabel's assistance.
- Percy's Big Mistake - Percy is frightened he will be sent to the Scrapyards.
- Thomas, Emily and the Snowplough - Thomas ignores Emily's advice.
- Don't Tell Thomas - The engines are organising a party for Thomas but are not sharing the secret with him.
- Emily's New Route - Emily thinks there is a monster in Black Loch.
- Thomas and the Firework Display - Thomas helps James deliver the fireworks before the display is called off.
- Gordon Takes Charge - Gordon shows off to Percy.
- Spic and Span - Thomas and Percy try to beat the big engines in a cleanliness competition.
- Edward the Great - Edward races Spencer to The Duke and Duchess of Boxford's Summer House.
- Squeak, Rattle and Roll - Gordon tries to go slow so his squeaking and rattling won't be heard.
- Thomas and the Circus - Thomas tries to pull the circus train all by himself.
- Thomas Gets it Right - Thomas gets competitive about his deliveries.
- As Good as Gordon - Emily gets to pull the Express and tries to do the job as good as Gordon.
- Fish - Thomas gets into bother on Arthur's coastal branch with a long line of trucks.
- Emily's Adventure - Emily learns to use her manners after a storm has hit Sodor.
- Halloween - Emily accidentally scares herself as well as Thomas, 'Arry, and Bert.
- You Can Do it, Toby! - Toby gets nervous when he has to look after Wellsworth.
- James Goes Too Far - James refuses to help his friends when he is given a very important job.
- Chickens to School - Lack of sleep gets the better of Thomas.
- Too Hot for Thomas - Thomas has to deliver ice cream ingredients.
- Percy and the Magic Carpet - Percy is disappointed about delivering a carpet until Salty suggests that it could be magic.
- 'Arry and Bert
- Annie and Clarabel
- Sir Topham Hatt
- Farmer McColl
- Sodor Brass Band
- Murdoch (does not speak)
- Trevor (does not speak)
- Lady Hatt (does not speak)
- Alicia Botti (does not speak)
- The Duke and Duchess of Boxford (do not speak)
- Henrietta (cameo)
- George (cameo)
- Caroline (cameo)
- Butch (cameo)
- Tiger Moth (cameo)
- Stephen Hatt (cameo)
- Bridget Hatt (cameo)
- Mrs. Kyndley (cameo)
- Jem Cole (cameo)
- Jeremiah Jobling (cameo)
- Farmer Trotter (cameo)
- The Refreshment Lady (cameo)
- Nancy (cameo)
- Cyril the Fogman (cameo)
- The Storyteller (cameo)
- Donald and Douglas (mentioned; deleted scene)
- Duck (music video cameo)
- Oliver (music video cameo)
- Rheneas (music video cameo)
- Rusty (music video cameo)
- Toad (music video cameo)
- The Fisherman (music video cameo)
- Bill and Ben (deleted scene)
- The Ice-Cream Factory Manager
- The Halloween Engine (does not speak)
- Kuffy the Clown (not named; does not speak)
- This was the first season of several things:
- The first season to not feature any new characters that would appear after their debut episodes.
- The first season made by HiT Entertainment and the first produced by Simon Spencer.
- The first season not to have Britt Allcroft, David Mitton, Mike O'Donnell and Junior Campbell involved in production.
- Sam Barlow's first season as story executive.
- The first season not to feature the Skarloey Railway since its debut, although Rusty and Rheneas made stock footage cameos in a song.
- The first season in which Terence does not appear.
- The first season which Duck doesn't appear since his debut in the second season.
- The first season to use the new opening titles and theme.
- The first season shot on DigiBeta technology, as opposed to 35mm.
- The first season that established the Steam Team.
- This was also the last season of several things as well:
- Abi Grant's second and last season as script editor.
- The last season broadcasted on CITV, however episodes from this season would still be shown on Citv until 2007. However, after ITV's revamp in January 2006, CITV didn't very often show them.
- The last season narrated by Leo Morimoto in Japan, as well as the last season to feature the original Japanese voice cast.
- The last season to be released on VHS in Australia.
- This was also the only season of a few things as well:
- Paul Larson's only season as script editor.
- The only season to use an extended version of the theme for the end credits.
- This season contained the 200th episode of the television series.
- CiTV had a special opening theme when they broadcasted this season in 2005. This theme was also used on some US DVD releases.
- The original opening is used in the Greek version.
- The engine rollcall was not shown on the CiTV broadcasts.
- Due to Seasons 5-7 never being shown in Finland, those viewers would not have known who Emily, Harvey, Arthur, Spencer, 'Arry and Bert, Salty, Elizabeth, Cranky, Farmer McColl, Murdoch and Alicia Botti are.