Star is one of the Umi-Clones. He's Geo's evil clone.
Star was created from some hair from Geo that were collected overtime by the Troublemakers. He's usually considered as the sneakiest of the clones.
Due to a flaw in the cloning process, Star has some differences from Geo. He does have blue hair, but his entire outfit is red and his skates are red and yellow. The shapes on his yellow Shape Belt are star, diamond, and another star, all of which are red.