The Galactic Empire employs countless Stormtroopers to rule the galaxy. Not all of these are regular soldiers — there are many specialized 'Troopers with specific skills and/or weapons. Unfortunately, some of these guys are more useful than others. Here are the Stormtroopers the Empire can probably let go.
Officially known as the Bomb Squad Trooper, these guys do what it says on the tin — they defuse bombs, and have special armor that's supposed to withstand explosions and shrapnel and all that other unpleasant stuff that comes out when bombs explode. These sound like a reasonable addition to the Empire's troops until you remember droids exist. The Star Wars Wiki claims Bombtroopers are more useful than droids because they can recover bombs after defusing them for Imperial intelligence, but come on — if you can build a droid who knows six million forms of communication or a scooting Swiss Army knife like R2-D2, surely someone can make a robot that can do this job instead of living beings. Fun fact: Bombtroopers wear helmets on their helmets. Adorable!
2) Nova Troopers
As befits their fancy name, Nova Troopers are part of the Emperor's honor guard, and thus get armor with a fancy black and gold color scheme. They're not to be confused with the Emperor's royal guard, the guys in red robes from Return of the Jedi who are the ones who actually seem to do most of the Emperor guarding. Somehow they're supposed to be both ceremonial and yet the most elite among Stormtroopers, which somehow leads to them being used to guard meaningful but unlikely-to-be-attacked places like Sith burial sites but also sent as commandos on super special missions. This seems a bit incongruous to me.
3) Incinerator Troopers
These are just Stormtroopers with Flamethrowers, which seems to be cheating. If you gave a Stormtrooper a rocket launcher you could call him a Rockettrooper, or if you gave him a broom you could call him a Sweeptrooper, but the fact of the matter is he's just a regular Stormtrooper who was issued something besides the standard blaster. No need to get all fancy with it, guys. That said, the really insane thing about Flametroopers is that they're all "psychopathic pyromaniacs." That's the official description. Like, the Empire seeks out pyromaniacs, gives them flamethrowers, trains them to like burning things even more, and then sends them places. This may be the worst idea in the galaxy.
4) ISB Troopers
The Internal Security Bureau… uh, troopers. If the idea of an Internal Affairs department for Stormtroopers doesn't make you giggle by itself, then you should know that one of their jobs is making sure Stormtroopers are being appropriately evil enough. For instance, the ISB was called in to investigate a 'trooper named Daric LaRone in the Allegiance novel, because he wasn't shooting civilians. This is deeply hilarious.
Much like there are Snowtroopers for cold planets and Sandtroopers for desert planets, there are Lavatroopers — excuse me, the official term is Magma Troopers — for planets covered in volcanoes, presumably like Mustafar. I would think that most of these planets don't need much guarding by virtue of the fact that they're, you know, covered in lava, but sometimes there are mines that need guarding or something. They look like regular Stormtroopers but are red, because... uh... lava, I guess. Lavatroopers may seem a bit specific, but not that crazy. That is, until…
6) Hazard Troopers
…you learn that something called Hazard Troopers exist, specifically as cyborgized Stormtroopers that are " deployed to worlds with extreme planetary climates and conditions, often wearing armor that fully sealed them from acidic, electromagnetic, biochemical, and other environmental threats." Oh, really? So extreme planetary climates like being covered in goddamn lava? Or being a super-cold ice world like Hoth? Why does the Empire have all these stupid extreme weather-specific Stormtroopers when they should just be sending these Hazard Troopers everywhere? Especially since these Hazard Troopers are also partially cyborgs.
7) EVO Troopers
But it gets more ridiculous! Hazard Troopers aren't to be confused with Environmental Troopers, who "able to survive and operate in the most hazardous of conditions such as extreme heat, acid rivers, and lightning" even though that sounds like the exact same goddamn thing. Besides the cyborg aspect, the biggest difference between the Hazard Troopers and the EVO Troopers is that the latter are chosen for their xenophobia and hatred of non-human races, which can't possibly help their environmental survival skills in the slightest, but is just the Empire being hilariously evil for evil's sake.
And just in case you thought all these "most hazardous of conditions" included radiation, they don't, because the Empire also employs Radiation Zone Assault Troopers for places they've nuked and yet want to make sure everyone is dead. Frankly, the real disappointment here is that the Empire has soldiers colloquially called Radtroopers but they don't ride skateboards and dirt bikes.
And for the cherry on the delightful sundae of redundancy in the Empire's Stormtrooper ranks, there are Minetroopers, who are apparently used specifically to guard mining equipment on Sevarcos II and nothing else. Apparently all other mining equipment on other planets — like, say, lava planets — are guarded by their environment-specific 'Troopers. Two fun facts about Minetroopers, courtesy of the SW Wiki: 1) their full title is Imperial Tunneling Underminers, you know, as opposed to all those open-air mines in the galaxy, and 2) "Their primary assignment was not necessarily to stop rampaging spice eels."
10) Shadow Stormtroopers
You'd think that the nickname for these guys would be Shadowtroopers, but apparently it's Blackhole Stormtroopers. Unfortunately, this isn't because they're trained to fight exclusively in black holes, but because they were commanded by an Agent Blackhole (don't even ask). Anyways, pretty much the only difference between these guys and regular Stormtroopers is the color of their armor, which is black. So I guess it's a victory for diversity, if nothing else.
These guys don't show up in the old Expanded Universe until many years after the movies, but I wouldn't expect to see Disney bring them back, because they are absurd. They are highly specialized Stormtroopers designed to hunt down and capture or kill Jedi, and have a special helmet that negates Force power of mind control, an electrostaff that can block lightsaber blades, and jet black armor. They're basically an entire squad of knock-off Darth Vaders, complete with capes and bad attitudes.
12) Terror Troopers
Another section of the seemingly infinite number of elite Stormtrooper divisions, Terror Troopers are a cross between General Grievous, Predator, and Freddy Kreuger. They're skilled martial artists and acrobatics, so they can jump all over the place, they have a personal cloaking device that allows them to disappear, and they have big clawed talons on their hands. They're basically the crazy ninja/assassins Stormtroopers that Emperor Palaptine probably doodled on his Trapper Keeper back when he was in fifth grade.
13) Riot Troopers
According to the Star Wars Wiki: "Riot troopers are stormtroopers created specifically to deal with civil unrest in various worlds to reestablish Imperial Order." Huh. You know what that sounds like to me? That sounds like every fucking Stormtrooper ever. Dealing with civil unrest and crowd control is practically a Stormtrooper's entire job description. Whether they're Snowtroopers or ISB Troopers or Lavatroopers, if a stormtrooper sees someone breaking the law or causing any kind of disturbance, they are supposed to shoot them. Having a group of Stormtroopers devoted to this one task that they're all supposed to be doing anyway is akin to creating a unit of Javatroopers — Stormtroopers whose sole job it is to make coffee. Is it really so specialized a task that it needs its own 'trooper?