Kelly was one of the first members of the Pack that Jack met, and he and Isobella both advised him to see the Foreman. A while later, he attempted to try and help Jack hold up a bridge that was collapsing, but by the time he had rushed over to the bridge, it had already collapsed.
Later, Kelly told the story of the One-eyed Truck to Percy and the rest of the Pack. Kelly also gained a fear of strong winds after an accident in which he was blown over, but he got over this fear after he rescued Isobella from falling off the Old Quarry Bridge. He later helped with the restoration of Great Waterton.
Kelly is good at heart and gets along with everyone. He is especially good friends with Isobella. He is seen by many as the team's leader, and is usually given the most dangerous work to do. He will not be rushed and understands that work of this kind takes extreme care. Kelly used to have a slight fear of strong winds, but he conquered that fear when he rescued Isobella.
Kelly is based on a Coles Vintage 1937 EMA 5 Austin K6 lorry.
Kelly is painted navy blue with red lining and a cream crane arm. His wheels are navy blue with red lining. He has the number "17" painted on his sides in cream.
- Kōzō Shioya (Japan; sixth season only)
- Kelly is one of the machines whose silhouette is pictured on the Pack's logo.
- Kelly has the same horn sound as Madge.