Series 15

The fifteenth season of the television series aired during March 2011 in the UK and between April and June in the US. There are a total of twenty episodes.

Episodes

 * 1) Gordon and Ferdinand - Gordon is embarrassed to be seen with Ferdinand whilst delivering the Lion of Sodor.
 * 2) Toby and Bash - Toby tries to find Bash a home on Sodor, but Bash misses his friends on Misty Island.
 * 3) Emily and Dash - Emily has to escort Dash to a steam fair, but thoughtlessly leaves him behind.
 * 4) Percy's New Friends - After his friends say they are too busy to play, Percy decides to make friends with the animals on Sodor.
 * 5) Edward the Hero - Edward wants to be a hero like Harold.
 * 6) James to the Rescue - James refuses to work with Toby as the rescue engine, but soon regrets his decision.
 * 7) Happy Hiro - Hiro is feeling homesick, so Thomas tries to cheer him up by taking him to Misty Island.
 * 8) Up, Up and Away! - Thomas and Percy deliver Mr. Bubbles' giant balloon.
 * 9) Henry's Happy Coal - 'Arry and Bert tease Henry about using special coal.
 * 10) Let it Snow - Whilst collecting logs for an animal shelter, Thomas sings the Misty Island Snow Song in hopes of making it snow.
 * 11) Surprise, Surprise - Thomas tries to hold a Christmas party at the Sodor Steamworks for his friends, but does not tell Victor.
 * 12) Spencer the Grand - Spencer disobeys orders and tries to puff to the Duke and Duchess of Boxford's Summer House in the fog.
 * 13) Stop that Bus! - Thomas takes Bertie on a tour, but Bertie has to pick up Dowager Hatt and her friends.
 * 14) Stuck on You - Thomas and Butch do not listen to Victor's instructions, so they do not know how to work Butch's new magnet.
 * 15) Big Belle - Belle's attempts to be friends with Toby only frighten the steam tram away.
 * 16) Kevin the Steamie - Kevin practices shunting so that he can take part in Thomas and Percy's game.
 * 17) Wonky Whistle - Thomas rushes off before his whistle can be properly fixed and scares Farmer McColl's animals.
 * 18) Percy the Snowman - Thomas promises to take a depressed Percy to pick up Sir Topham Hatt, but whilst Thomas is finishing his jobs, he only succeeds in covering Percy in snow.
 * 19) Tree Trouble - The Diesels and Thomas compete to find the best Christmas tree for the Steamworks and Dieselworks.
 * 20) Fiery Flynn - Flynn tries to impress the Diesels with his bravado with potentially disastrous results.

Characters

 * Thomas
 * Edward
 * Henry
 * Gordon
 * James
 * Percy
 * Toby
 * Emily
 * Spencer
 * Rosie
 * Whiff
 * Stanley
 * Hiro
 * Charlie
 * Bash and Dash
 * Ferdinand
 * Diesel
 * Mavis
 * 'Arry and Bert
 * Salty
 * Victor
 * Rocky
 * Bertie
 * Butch
 * Kevin
 * Harold
 * Captain
 * Cranky
 * Sir Topham Hatt
 * Lady Hatt
 * Dowager Hatt
 * Farmer McColl
 * The Duke of Boxford
 * Mr. Bubbles
 * The Sodor Search and Rescue Centre Manager
 * The Maithwaite Stationmaster
 * Workmen
 * Schoolchildren
 * The Small Boy
 * The Blonde-haired Boy
 * The Duchess of Boxford (does not speak)
 * Scruff (cameo)
 * Annie and Clarabel (cameo)
 * Henrietta (cameo)
 * Trevor (cameo)
 * Stephen Hatt (cameo)
 * Bridget Hatt (cameo)
 * Mr. Percival (cameo)
 * Jem Cole (cameo)
 * Alicia Botti (cameo)
 * Sodor Brass Band (cameo)
 * The Photographer (cameo)
 * The Bargeman (cameo)
 * The Fireman (cameo)
 * The Knapford Stationmaster (cameo)
 * The Teacher (cameo)
 * The Bird Watcher (cameo)
 * The Railway Inspector (cameo)
 * The Tree Specialists (cameo)
 * Three Sodor United Players (cameo)
 * Farmer Trotter (mentioned)

Characters Introduced

 * Belle
 * Flynn
 * Den
 * Dart
 * Norman
 * The Railway Coal Inspector
 * Dowager Hatt's Friends (do not speak)
 * Paxton (cameo)

UK and AUS

 * Michael Angelis as the narrator
 * Ben Small as Thomas, Toby, and Ferdinand
 * Teresa Gallagher as Emily, Rosie, Belle, Mavis, Lady Hatt, and the Ginger-haired Boy
 * Keith Wickham as Gordon, Henry, James, Percy, Edward, Whiff, Dash, Salty, Den, Norman, Harold, Captain, Sir Topham Hatt, Dowager Hatt, Mr. Bubbles, and the Railway Coal Inspector
 * Matt Wilkinson as Spencer, Stanley, Charlie, Victor, Bash, Cranky, Kevin, Farmer McColl, the Duke of Boxford, the Maithwaite Stationmaster, and the Sodor Search and Rescue Centre Manager
 * Rupert Degas as Bertie, Butch, Dart, and Flynn
 * Togo Igawa as Hiro
 * Kerry Shale as Diesel, 'Arry, and Bert

USA

 * Michael Brandon as the narrator, Diesel, and Mr. Bubbles
 * Martin Sherman as Thomas and Percy
 * Jules de Jongh as Emily, Rosie, Mavis, and Lady Hatt
 * William Hope as Toby, Edward, Whiff, Dash, the Duke of Boxford, and the Maithwaite Stationmaster
 * Glenn Wrage as Spencer, Charlie, Ferdinand, Rocky, Cranky, Butch, and the Sodor Search and Rescue Centre Manager
 * Kerry Shale as Gordon, Henry, James, Bash, Kevin, Harold, 'Arry, Bert, and Sir Topham Hatt
 * Keith Wickham as Dowager Hatt, Captain, Salty, and Den
 * Ben Small as Stanley
 * Teresa Gallagher as Belle and the Ginger-haired Boy
 * Rupert Degas as Dart, Flynn, and Bertie
 * Togo Igawa as Hiro
 * David Bedella as Victor

Trivia

 * This season was supposed to be shown after Day of the Diesels, but was brought forwards for unknown reasons.
 * Most of the episodes of this season were written by former head writer, Sharon Miller.
 * This was Christopher Skala's last season as executive producer.
 * This was Jo Jordan's last season as creative producer.
 * This is the last season not to feature the Skarloey Railway engines since their debut, following the eighth, thirteenth, and fourteenth seasons.
 * Percy's whistle now budges up and down when he uses it.
 * This season marks Butch's first speaking role.
 * Rupert Degas is now part of the voice cast.
 * Jules de Jongh is mentioned in the UK credits despite not having a role.
 * On Netflix UK, this series is listed as being season 13.
 * This is the only season where Thomas does not get his name titled in any episode.