Thomas is a very cheerful blue engine.
Season 1 - Luke and the Special Party, Races, Paxton Helps Out, Where's BoCo?, Bulgy the Vegetable Bus , Duck and the Field Trip (cameo), The New Diesel Fuel (does not speak), Repairing Old Slow Coach, Bears (cameo), Bertie and the Fog ,Sleepy Merrick (cameo), Thomas and the Kitten, Cranky Cranky (does not speak), Dave the Diesel (cameo), Salty Fries (cameo), Bothered Byron, James and the Ice Cream, Donald, Douglas and the Fallen Tree, The Lightning Tree, and Dash and the Fair (cameo)
Season 2 - Unique Stafford (does not speak), Hay, The Magic Railroad, Flora's New Coach (cameo), Wobbly Wheels, Tim and Tom (cameo), Winston the World's Smallest Car, Daisy and the Chickens (cameo), Sugar (does not speak), Paxton in Trouble, Sodor Blackout (does not speak), A Day in the Life of Culdee (does not speak), Hiro goes Home, Kelly's Stormy Day, Off to the Scrapyards (cameo), and Thomas and the Christmas Surprise
Season 3 - Thomas and the New House, Murdoch and the Heavy Goods Train, The Forest Fire (cameo), Apples, The Rude Truck, Red Paint, Grumpy George, Replacing the Logging Locos, Scruff's Dirty Job, The Gold Mine, The Mail Depot, Harvey Joins the Team, Sir Handel, Rusty and the Runaway Boulder, Rheneas and the Bridge (cameo), Oliver and the Old Mansion (cameo), Dennis and Norman, The Adventure, Musical Whistles, Snowmen, and Duke Returns
Season 4 - Hiro's New Snowplough, Thomas and the Fireworks, Peter Sam's Delivery, Diesel and the Barge, Muddy Thomas, The Return of D199, Fishy Trouble (does not speak), The Trouble with Trucks, Tiger Moth the Show-off, The Country Show, Stanley and the Old Scrap, Runaway Coach, James the Really Splendid Engine (cameo), Boat Race (cameo), and The Final Race
Season 5 - Which Way?, James and Dennis, Thomas and the Dare, Duncan and the Ghost Engine, Toby and Rheneas, James' Bee, Different Languages! (cameo), Henry Go to the Sea, Down by the Docks and Hiding in the Hills