Timothy is a cheerful little engine who works at the China Clay Pits with Bill and Ben. Timothy is very friendly and really wants to be helpful and useful, but he can be a little naive and gullible, a trait which Bill and Ben love to take advantage of. But no matter how many tricks they play on him or how much they tease, Timothy just dismisses Bill and Ben as silly engines and gets on with his job. He likes working at the Clay Pits and is great friends with Marion, the Railway Steam Shovel. Timothy relies on oil to heat his boiler, so he has a special supply at the Clay Pits, but this is an unusual fuel on the island so is not to be found just anywhere.
Timothy is one of the smaller engines on Sodor, a little oil burning steam locomotive who works at the China Clay Pits with Bill, Ben and Marion.