Until 2008, all characters were voiced by the narrator. Individual voices were given to the characters following the switch to full CGI animation in 2009 until the series ended in 2021.
Emily, Mavis (Season 13–16), Lady Hatt, The Duchess of Boxford, Stephen Hatt ("Diesel's Special Delivery"), Bridget Hatt, Bridget Hatt's Friends, Some Children, Little Boy in White and Light Blue Stripes Shirt and Red Shorts, The School Children, Teacher, The Laundry Lady, Little Girl in the Red Dress, The Ginger Haired Boy ("Pop Goes Thomas","Diesel's Special Delivery","Emily and Dash","Percy the Snowman","Emily's Winter Party Special", and "Pouty James"), The Blonde Haired Boy (Season 15 and 18), and The Blonde Haired Girl
US/UK
Emily ("4-D: Bubbling Boilers" and the singing voice for "The Great Race" only), Caitlin (Season 20 onwards), and Allicia Botti
Emily, Lady Hatt (Season 13, "Day of the Diesels" and Season 15), Mavis (Season 13–16), The Duchess of Boxford, Stephen Hatt ("Diesel's Special Delivery"), Bridget Hatt, Bridget Hatt's friends, the teacher, the laundry lady, little boy in light white and light blue stripes shirt and red shorts, some children, the school children, little girl in the red dress, the blonde-hair girl, and the blonde-hair boy
US
A blond-haired girl
"Very Important Sheep"
A blonde-haired boy
"Very Important Sheep" only
UK/US
Belle, Frieda, Gina (The Great Race only), Mavis (FQC 1), Annie, Clarabel, Judy, Cassia (Big World! Big Adventures! only), The Duchess of Boxford ("Percy's Lucky Day" only), Lady Hatt ("The Afternoon Tea Express" only and Season 21 onwards), the teacher (Season 18 only), the ginger-hair boy, the shouting little boy, the lady with the big hat, some passengers, the Knapford Station speaker ("The Adventure Begins"), some children ("The Adventure Begins" onwards), the school children ("Lost Property"), Stephen Hatt, Bridget Hatt, the lady in the blue dress, the barrow fan ("Reds vs. Blues" and "Useful Railway"), Albert's wife ("Thomas the Babysitter" and "Unscheduled Stops"), the lady in spring green dress, the female puppet show entertainer, little girl in the turquoise dress with pink flowers, the lady in the white dress and gray vest, the lady in the white shirt, light brown skirt and hat, the lady in the grayish white shirt, blackish gray skirt, and white pearl necklace, the chubby little boy in dark green shirt and dark gray shorts, the lady in the yellow dress and hat, The Blonde Haired Girl, The Lady in Red and Indigo Hat and White Dress with Gray lines, Female Passengers, Madeleine's Mother, Brenda, and The Sodor Rangers
Carlos (Big World! Big Adventures! onwards), The Brazilian Tank Engine, Fernando, the Brazilian Troublesome Trucks, Emerson, the Brazilian Dock Manager (Big World! Big Adventures!), and the Crowd (Grudge Match)
Edward, Toby, Stephen Hatt ("Thomas and the Runaway Kite" only), Whiff, Bash, the Troublesome Trucks, Rocky, Farmer McColl, the Duke of Boxford, the blond-haired boy ("Merry Misty Island" and "The Way She Does It" only), the Maithwaite stationmaster ("Double Trouble" and "Wonky Whistle" only), the man at the fire ("Race to the Rescue"), the Dock Manager and the Wellsworth Station worker
UK/US
Iron Bert (series 16 onwards), a railway inspector, a steamworks worker ("Wonky Whistle"), 2 farmhands ("Wonky Whistle"), a workman ("Toad and the Whale"), Passenger, and Farmer McColl ("Philip's Number" only)
Porter, Jack[broken anchor], Racing Car #3 and the Dock Manager ("Tale of the Brave" only)
US
Charlie
"The Great Race" only
Butch
Series 17 to 24.
UK/US
Duck, Ryan (series 20 onwards), Dart (Season 17 onwards), Paxton ("Blue Mountain Mystery" onwards), Peter Sam, "The Third Slip Coach", a workman (Journey Beyond Sodor), a railway inspector (Season 17), the bird watcher ("Who's Geoffrey?"), and a Child
Porter (US; series 17 onwards/UK; "Pouty James" and "Cranky at the End of the Line" only), Stanley ("The Truth About Toby" only), Racing Car #3, and Jack (US only)
Rachael Miller
UK/US
Rebecca, Angelique, Isla, The Lady with the Big Hat (Outback Thomas), The Teacher (Outback Thomas and Cyclone Thomas), some Passengers (Outback Thomas), The Lady in Chartreuse Dress, Madeleine, Prince Charles, and Dr. Hetty
Joe Mills
Douglas,[2]Oliver, Toad, the Welsh bird watcher ("Thomas and the Emergency Cable"), a Knapford Station yard workman ("Toad and the Whale"), and a Passenger ("Confusion Without Delay")
James (US; "The Adventure Begins" onwards/UK; "Tit for Tat" onwards), Donald (Season 20 onwards), Raul (The Great Race only), Axel, Étienne, Flynn (Season 19 onwards), Hugo, the Troublesome Trucks, Bradford, The Great Railway Show Announcer, some Passengers, The Bird Watcher ("The Railcar and the Coaches"), Fergus Duncan, The Welsh Bird Watcher ("Mike's Whistle"), The Thin Clergyman, The Red Sea Serpent, the first Tiger Hunter, The Film Crew Leader, Owen, the Crown Thief #1, Elephant Carer, Bernie, the Washdown Worker, and Professor Freidrich
Henry, Gordon, James (US: "Hero of the Rails"-Season 18) Dash, Scruff, Harold, Max, Kevin, Sir Topham Hatt ("Hero of the Rails" – Season 18), Sir Lowham Hatt, Mr. Percival, Farmer Trotter, The Maithwaite stationmaster ("Time For a Story" and "A Blooming Mess"), a railway inspector, the photographer (Season 16), the railroad coal inspector, the zoo keeper and some workmen
UK/US
Flynn ("Toad and the Whale" only), Kevin ("Hasty Hannah" only), Diesel (US; series 19 onwards/UK; series 13 onwards), 'Arry, the Troublesome Trucks, some groaning passengers ("Calm Down Caitlin"), the man on the bridge, and Headkeeper Jack
Edward, Henry, Gordon, James ("Hero of the Rails"-"The Great Race"; excluding "Tit for Tat"), Percy ("Hero of the Rails"-"Sodor's Legend of the Lost Treasure"; excluding Series 19), Whiff, Dash, Harold, The Thin Controller, the railway coal inspector, the man at the fire, the Wellsworth Station Worker, the Fat Controller's Assistant, some Workmen, some Passengers, Gator's Driver, and a Steamworks Workman
UK/US
Harvey, Glynn, Salty, Den, Norman, Stafford, Skarloey, Sir Handel, Arlesdale Bert, Bertie, Captain, Sir Topham Hatt/The Fat Controller (UK; "Hero of the Rails"-Series 24/US; "The Adventure Begins"-Series 24), Dowager Hatt, Sir Lowham Hatt, Lord Callan, the photographer ("Wild Water Rescue"), a Railway Inspector, the Great Composer, the Maron Station Speaker, the Wellsworth Stationmaster, Thomas' Guard, the Grumpy Passenger, Father Christmas, the Groundsman, Tom Tipper, Gordon's driver ("The Adventure Begins"), James' guard ("The Adventure Begins"), a Knapford station worker ("The Adventure Begins"), some Workmen, some Signalmen, the dock manager ("Who's Geoffrey?" only), a Sodor search & rescue centre worker ("Toad and the Whale"), the policemen, a Diver ("Sodor's Legend of the Lost Treasure"), Some Passengers, Albert ("Thomas the Babysitter"), Mr. Bubbles, the Welsh Bird Watcher ("Sidney Sings and Three Steam Engines Gruff"), one of Dowager Hatt's friends ("Best Engine Ever" and "Sidney Sings"), the Museum Manager, the Male Puppet show Entertainer, Willie, Franz, the Station Announcer, a Child ("Gordon Gets the Giggles"), The Mainland Stationmaster, Thomas' Driver, Thomas' Fireman, and the Elderly Man.
Spencer, Stanley, Charlie, Bash, Scruff, Rocky, Cranky, Carter, Butch[broken anchor] (Season 16 onwards), Kevin, Tony, Stephen Hatt ("Thomas and the Runaway Kite"), Farmer McColl, the Duke of Boxford, the photographer (series 16), the Maithwaite stationmaster, Farmer Trotter, the Knapford stationmaster, the bird watcher ("Henry's Good Deeds"), the blond-haired boy ("Merry Misty Island"), the dock manager, a railway inspector, some dock workers, the island inspector, the Sodor search & rescue centre manager, the Blue Mountain Quarry workman, the zoo keeper and the man with the hat
UK/US
Ben, Diesel 10, Winston, Rusty, Merrick, Captain Joe, some workmen, Male Passengers, and The Man in Blueish Grey Shirt, Whitish Cream shorts, and Aquamarine hat
Spencer, Ferdinand, Charlie (Season 13 - 15), Cranky, the Sodor search & rescue centre manager, Sir Topham Hatt's Assistant, Gator's driver and a Steamworks worker
