Jack is a young red front loader that works for Miss Jenny Packard.
When Jack first arrived on Sodor, the Pack was working very hard to build a new Quarry Site for the Railway. Jack was anxious to work, but jumped in where he didn't belong. Darting too quickly, he took a tumble on the hill and fell into a heap of barrels and crates. After this spectacle, Miss Jenny was not sure if Jack was ready to join the pack, so the friendly little front loader was anxious to prove himself.
His chance came sooner than expected! When a bridge keystone fell loose, Thomas was dangling over the edge with a line of trucks! Jack jumped into action once more (this time for the right reasons!) and used his front loader to hold the bridge into place. This gave Thomas enough time to back away, and Jack reversed before the stone arch could crush him. His front loader was badly twisted, but Miss Jenny was very proud. It was after thus heroic act that Jack has become a permanent member of the team!
When Bear and his passengers were buried in an avalanche, Jack and Fergus were dispatched to come to his rescue! At first, Bear gave Fergus all of the credit, but Jack politely reminded the Diesel who really cleared away the snow!
Jack is a very friendly and optimistic red front loader that loves to work. He in anxious to impress Miss Jenny and always tries his best. Sometimes, though, Jack is so enthusiastic he jumps into situations where he does not belong. This can cause trouble, but he has shown the capacity to know his place when he is needed most. He is willing to make sacrifices for the greater good, making him a genuine hero and a good friend indeed.
- Season 1: Snow Blind (remastered version cameo)
- Season 2: Hibernation, Blunderbuss (cameo), Luke and Millie's Blue Mountain Adventure, Aura of Menace, Henry and Kurt (cameo), All the World's a Stage (cameo), Swashbuckler (cameo)
- Season 3: Marion Saves the Day (cameo), Ice Breaker (cameo), Chivalry is Dead (cameo), Percy and Asbestos (cameo)