Thrax is a viral pathogenic agent that came from the filthy egg that Frank ate that was covered in chimp saliva and that also fell on the ground. Being the main antagonist of the 2001 film Osmosis Jones, Thrax is also a deadly virus who wants to kill cells so that his records can go into the medical books.
Thrax is very sadistic, murderous, self-centered, good looking, and deadly. He's shown to lose his temper when things don't go as he hoped. Thrax also has no problem deceiving and even killing his own allies.
Thrax is also shown to be intelligent, as well as knowledgeable about how to take down a human being, possibly implying that he killed more than the three people mentioned in the movie. He was able to use his prior experience to near lethal effect, making it appear that he was a common cold virus until he attacked Frank's hypothalamus.
Thrax arrives in Frank on the egg that he dropped on the ground at the zoo. The first thing he does is destroy the cells that found him in order to eliminate witnesses, despite the fact that Artie's coworker surrendered. He then sets a saliva boat on fire and causes a sore throat. He then ventures to the left armpit to build a gang to help him take down Frank. After killing the current mob boss, Thrax and his new gang go to the dam to cause a runny nose. After he and the gang escape, Thrax sets up a meeting at the Zit to gather new crew members for the final stage of his plan. There he confronts Ozzy and Drix who are almost successful in killing him. Thrax and two of his cronies survive the explosion at the Zit and set up shop at an old adrenaline station in the ingrown toenail. After one of the henchmen suggest that they incubate until they can get more men, Thrax kills them and goes by himself to attack Frank's hypothalamus gland. He escapes Frank as his fever quickly climbs to 108 degrees. As he escapes though, Ozzy follows him and they both land and fight on Shane's eye. After a struggle, Osmosis Jones tricks him into jamming his claw into one of her false eyelashes, which falls into a beaker of rubbing alcohol. Thrax falls with the false eyelash, and disintegrates. His claw is one of the last things to go.
- Thrax is voiced by Laurence Fishburne.
- The fact that he resembles no known disease in real-life, that the doctors who were stabilizing Frank had no idea what was wrong with the latter and that there are apparently no records of him in the medical books implies Thrax was an entirely new type of virus that developed.
- Thrax's name is similar to the disease anthrax, which is EXTREMELY fatal to humans.
- During the film, it's possible that Thrax killed Frank's wife, as Frank lost his wife to an unknown disease.
- Thrax was referred to as La Muerte Roja, which means The Red Death. However, Thrax differs greatly from the disease from Masque of the Red Death by Edgar Allen Poe. That disease marked its presence by severe external hemorrhaging and death within hours. Thrax, on the other hand, masqueraded as a cold virus, and according to his boasting in the Zit, the quickest he'd ever killed someone was 72 hours.
- Thrax is described as a tall, extremely virulent, and unusually powerful pathogenic agent.
- According to Thrax, out of the cells in all the people he's taken down, Osmosis Jones was the only cell who had ever figured out his plan.
- Interestingly, despite Thrax using his claw to set things on fire with his claw, it would appear that Thrax is unable to defrost his claw when frozen, as shown in the fight scene in the uvula.
- Despite the mixed reception of the film, Thrax is a widely popular character with fans on internet websites such as DeviantArt, Youtube, FanFiction, etc.