Jack is a character that only appeared in Blue's Big Treasure Hunt. He is voiced by the late Gregory Hines.
Jack jumps past Steve and Blue. They look for him and could not find him. Jack appears and has a problem. The nursery rhyme starts with "Jack be nimble, Jack be quick". Steve and Blue had to figure out what Jack had to jump over. The answer was a candlestick. The whole nursery rhyme is: "Jack be nimble, jack be quick, Jack jump over the candlestick." Jack had a scroll for Steve and Blue to thank him for his help.