Rex is the pet turtle that the Skipper races against Mr. Howell's turtle, to whom he often loses. Gilligan names him after Rex Stonecipher, an old childhood friend. Rex seems to really like carrots, which fall into short supply after Mr. Howell buys them all up. He also likes tree moss, stuffing himself full of it before a race and losing once more, which places Gilligan in servitude to the Howells. After some switching around with his opponent, Rex loses even Gilligan's pocketknife to Mr. Howell, but the races eventually come to end after Mr. Howell sees no longer wagering opportunity between himself and the Skipper.
- Rex looks like a common box turtle which is native almost entirely to North America and not indigenous to the South Pacific.