Bill and Ben the Tank Engine Twins are characters in the television series.
- Season 3 - Thomas We Love You
- Season 4 - Thomas' Anthem Grand Finale, The Island Song (one only), and Really Useful Engine (one only)
- Season 5 - Night Train, Accidents will Happen (one only), Every Cloud has a Silver Lining, It's Great to be an Engine, Sir Topham Hatt, and Come for the Ride
- Season 6 - Little Engines, Down by the Docks, and Winter Wonderland
- Season 7 - Troublesome Trucks and Salty
- Season 10 - Doing it Right
- Season 17 - Hey, Hey Thomas and On a Journey Today
- Season 18 - The Best Friends Express
- Calling All Engines! - Trying
- Tale of the Brave - Let's Be Brave
- They only appear in Calling All Engines! through a cameo in the music video, Trying.