The cast of the webcomic String Theory
The main protagonist. A man who, despite being the youngest recipient of a Ph D in quantum physics in history at age 19, has spent much of his life (the following 15 years in fact) toiling away in obscurity. He currently works deep underground in Station 12, New Mexico, and hasn't been outside on the surface for years. Described as an aggressive jerk, alcoholic and part-time drug addict, Schtein is generally disgusted by people due to his anthropophobia, agoraphobia and fear of germs. Because of these phobias, he wears gloves constantly when outside his own home. Although he acts like a jerk a lot of the time, Schtein has a lot of hidden insecurities. After a lab accident that left him blind, he was outfitted with experimental cybernetic eyes but foolishly declined an upgrade from the black and white vision version to full color vision. Owns a talking, sentient cat, a survivor of a gene-splicing experiment on kittens.
- The Alcoholic: One of Schtein's many issues.
- Disappeared Dad: To his estranged daughter, Alice
- Eye Scream: The outcome of Schtein's failed experiment before the beginning of the comic.Schtein: The only thing that happened to me is a plasma arc burnt the front of my face and melted my eyes out of their sockets.
- Functional Addict: Considering all the drugs he's on, it's astonishing Schtein can manage to walk, let alone work as a super-scientist for the government.Schtein: I sometimes take amphetamines. You know, to stay alert...but that's more of a casual use thing...Um, then...sometimes I take sleeping pills. You know, the speed sort of keeps me awake. Maybe a little pot, and if someone offered me coke at a party I wouldn't exactly say no, uh...Spent as entire weekend when I was nineteen tripping balls on Ayahuasca...that's not important though, is it?
- Hates Being Touched: Schtein is hypersensitive to touch and is absolutely dependent on his gloves.
- Hearing Voices: Happens when Schtein suffers drug withdrawal. It is suitably disturbing.
- Herr Doktor: Though he doesn't seem proficient in German and, in fact, switches to French in stressful moments.
- Jerkass Woobie: His mother abused him, he has terrible luck with women, and the poor guy gets beaten up so often in prison...
- Mad Scientist: Schtein seems to be hurtling towards this as the comic continues.
- Mommy Issues: She hasn't been discussed much, but it's certain that Schtien's mother was both physically and emotionally abusive.
- Red Eyes, Take Warning: Schtein, after he loses his initial eyes. Most probably foreshadowing.
- Sinister Schnoz: His nose is rather large.
- Ugly Cute: Schtein, for some.
- The Unsmile: When he's not scowling, he defaults to this. It develops into an impressive Slasher Smile though his Start of Darkness. When he smiles sincerely, the effect on his face is remarkable.
Dr. Schtein's assistant in the first chapter. Spent the second chapter searching for him, but at the present believes he's officially dead. Originally hailing from the UK (but travelled to the US at eighteen to study at Cambridge, Massachusetts), Delia is a young woman ostracised from scientific circles on the eastern coast - which is a shame considering her incredible talent. Delia is a hard worker to a fault. While seeming outwardly scattered and absent minded, this is in fact due to her mind being so absorbed in her tasks. She also has the tendency to speak her mind as thoughts come to her, even if they are quite rude.
Dr. Schtein's beleaguered college roommate. Works for a shady company, in an undetermined position. Had an eye scratched out shortly before his first appearance in the comic. Laurence is Schtein's former brother-in-law and Alice's uncle.
One of Dr. Schteins fellow inmates. For over ten years, Phineas Armastus, nicknamed Prof. Pain, was a professor who taught various courses in psychological neuropathy. Obsessed with the concepts of pain and suffering, and how they affect the human mind, he believes that only pain and suffering could make us strong. After not being satisfied with how his after school program went after a year, he decided to take his experiments one step further, with a deadly turn: students went missing, and there were dead bodies. He's currently working in the prison infirmary.
- Beauty Mark: Phineas has one on the left side of his face.
- Berserk Button: Don't tell him you haven't heard of him.
- Blood Lust: The man is a cannibalistic serial killer, after all.
- From Nobody to Nightmare: Phineas was originally just a professor. And then the students started disappearing...
- I'm a Humanitarian: Not confirmed, but the other inmates seem to think so, and Phineas never denies it.Jayjay: Do you know what that guy did to get in here? Him and his wife were murdering students, doing creepy sex things to their corpses, and then eating them.
- Mistaken for Gay: 
- Murder Is the Best Solution: This seems to be Phineas' general attitude.
- Scary Shiny Glasses: As if he wasn't scary enough...
- Serial Killer: Confirmed by Dirk themself.
- Nausea Fuel: Jayjay considers Phineas to be this.
- Nerd Glasses
- Odd Friendship: He seems to be developing this with Schtein.
- Only Sane Man: Jayjay comes off as a normal guy who happens to be locked up with hallucinating, cannibalistic, drug-addicted psychopaths.
- Badass Mustache: It is very impressive.
- Bald of Evil: Goes well with his skinhead persona.
- Dumb Muscle: His intelligence is probably greater than that of his gang, but compared to the other characters (Schtein, Armastus, etc.) he could be considered dumb.
- Karmic Death: Schtein slits his throat with the same shank Mac Manus used to stab him.
- Tattooed Crook: Mac Manus is covered with tattoos; he even has one on his head.