The twelfth season of the television series aired in 2008. The twenty episodes were narrated by Michael Angelis in the UK and Michael Brandon in the US.
- Thomas and the Billboard - Diesel obscures Thomas in a photograph of the engines.
- Steady Eddie - Edward takes the Great Waterton water wheel on the scenic route to show off to his friends.
- Rosie's Funfair Special/Rosie's Carnival Special - Rosie and Emily are pulling a train for a fair, but Rosie wants to pull it alone.
- Mountain Marvel - Peter Sam rushes to finish his jobs in order to hear a tale about Proteus from the famous storyteller, Miss Marvel.
- Henry Gets It Wrong - Henry worries that the workmen are going to cut down the wishing tree.
- Heave Ho Thomas! - A large new engine called Hank arrives, but Thomas is determined not to need his help.
- Toby's Special Surprise - Toby wants to make an impression by searching Sodor for something special.
- Excellent Emily - Emily becomes arrogant after receiving praise from the Fat Controller.
- The Party Surprise - Freddie decides to reorganize a winter party from Mr. Percival's house to the Wharf as a surprise for Colin the crane.
- Saved You! - Thomas wants to prove his heroism when he learns a fireman is to be honoured.
- Duncan and the Hot Air Balloon - Mr. Percival's twins are getting a ride in the Hot Air Balloon for their birthday, but Duncan wants to take them himself.
- James Works It Out - When James ignores Hector's advice, he gets caught in bad winter weather.
- Tram Trouble - Toby and Flora are heading a parade at Great Waterton; Thomas thinks Toby would rather lead the event on his own and tries to distract Flora.
- Don't Go Back - Thomas and Diesel race backwards.
- Gordon Takes a Shortcut - Gordon gets lost while taking a shortcut and refuses to ask for help.
- The Man in the Hills - Thomas and the narrow gauge engines collect presents for Mr. Percival's birthday.
- Thomas Puts the Brakes On - Thomas' brakes malfunction while delivering bricks to repair a bridge.
- Percy and the Bandstand - Percy is tasked with bringing Lady Hatt to a surprise party - but the unknowing Lady Hatt tells him to go elsewhere.
- Push Me, Pull You - Skarloey refuses Rheneas' help to pull a train for a puppet show and ends up playing the trucks' games.
- Best Friends - Thomas tries to avoid telling Percy he has been given a job Percy wants to do.
- This is the last season to use models and clay faces, however the clay faces are only used in background shots.
- This was Sharon Miller's first season as head writer.
- This is the first season to only have twenty episodes.
- This is the last season to be filmed at Shepperton Studios.
- This is the last season to feature songs by Ed Welch.
- This is TV series veteran Steve Asquith's final season.
- This was Pete Atkin's only season as voice director.
- Pierce Brosnan was originally going to narrate this season, but was later replaced by Michael Angelis and Michael Brandon for unknown reasons.
- This was the last season to have all of the characters voiced by the narrator.
- This is the first and only season not to be shown on Japanese TV, but has been shown exclusively at Thomas Land's 3D Theatre in Japan.
- This season was never shown in Norway.
- In the UK, this season was supposed to be shown after The Great Discovery, but was brought forwards for unknown reasons.
- Several characters returned in this season, including Duck, Oliver, and Stepney.
- Aside from the Teacher and the tree specialists, all of the characters introduced in this season have only ever appeared in their debut episodes.
Thomas in the Island of Sodor opening