Osmosis "Ozzy" Jones an over-zealous white blood cell and the protagonist of the film. Osmosis' positive reputation was destroyed when he saw a salmonella pathogen about to enter Frank through an ingested raw oyster and reacted by causing him to vomit onto Mrs. Boyd. Since this incident, he was suspended for unnecessary force and placed in out-of-the-way patrols. Therefore he takes any opportunity to be able to make a difference. It is because of this that he is not believed about Thrax’s infection. Being a cell, Ozzy is able to combine his eyes into one, to ooze under doors, and to contort his body drastically, which allows him to escape Thrax's fate at the film's climax. It was shown in one scene that if enough force is exerted then his morphing will go back to normal as when Ozzy disguised himself as a germ to learn about Thrax's plan, his cover was blown when Thrax's henchman Lard affectionately but roughly patted Ozzy on the back and causing his wallet with his police badge to fall from his jacket and onto the table and expose his real identity.Ozzy is described by some female viewers of the film as a very attractive white-blood cell, He teams up with a cold-pill named Drix to help kill Thrax, the germ that is causing the cold-like symptoms Frank is experiencing. Drix unlike Ozzy, is very sweet and gentle, with a tender side.