Mari is a female thresher shark who as a member of Rogue Shiver served some great purposes. She was the one who kept Rogue Shiver together even when all of her friends (to be specific, mainly Gray, Barkley, and Striiker) bickered with one another.
Species: Thresher shark (no known specific thresher)
- In the Shark Wars ARC (Advanced Reader's Copy), Mari's name was Finn, which is why Mari is called 'Finn' sometimes in the book.
- Although they are usually enemies, Mari and Velenka sometimes put away their differences and talk to each other about their troubles.