Can A Thrown "Ninja Star" Kill You

Let’s not debate whether or not those “Ninja Stars” that you can buy at head shops and comic book shops are/were real weapons used, by ninjas or otherwise. I’m simply asking about the modern, stainless steel “weapon” that you can buy for a few bucks.

Assuming the assailant is a fully-trained expert in getting the maximum velocity out of his throw, can one of those things actually kill you?

If it hit you in the neck it might nick the jugular and/or the carotid.

Other than that though, I think the blades would have to be poisoned to do much.

ETA: Wikipedia says that they were minor weapons that could be improvised from various pieces of metal, were often used as hand-held blades, and in general were expendable missiles mainly used to distract and harass. I think the idea that you could throw one, it would embed itself in an opponent’s chest, and they would fall over dead is mainly (John) woo.

Thrown hard enough, most of them could penetrate the skull and kill. A temple shot or one to the occipital region would be deadly. In fact, just about the only fatal hit would be in the neck and head region. Anywhere else and there’s too much body mass between the star and something vital.

I mean, Ricky Jay can throw a playing card to stick in a watermelon. Surely somebody who was good at it could get even a shitty throwing star into your eye or your throat.

I have to question both of these statements. The typical 3 to 3-1/2 inch diameter “ninja throwing star” with six to eight points has an effective blade length of less than two inches; worse yet, the geometry of the star ensures that the adjacent tips will come in contact with the body and stop the leading tip from penetrating even to its full depth. Another problem is momentum; a properly overhand thrown knife enters the target tip slightly up, digging forward with its rotational momentum contributing of the long arm contributing the maximum mass to penetration. This can be seen in the fact that longer blades of the same weight will penetrate deeper (although they take more skill to throw correctly). A throwing star has no long axis; with the mass disturbed symmetrically about the center of mass, it provides a lot less effective penetration force because of the lower angular momentum per unit mass. This, combined with the typically small mass of throwing stars limits their penetration ability. It should be noted that actual shuriken were derived from trowels, awls, needles, and other nominal implements and tools, and were never intended as primary killing weapons, but rather devices to distract or temporarily disable an opponent while making a primary attack. “Ninja throwing stars” became popularized because of the spate of ninja-themed movies in the late 'Seventies and early 'Eighties, and also because throwing this type of “weapon” into soft pine or styrofoam is much easier to master than a thrown knife or heavy dart.

As for the injuries to the neck and head, the jugular vein and carotid artery are nowhere near as vulnerable as most people believe. The bulk of the vessels are protected by a thick mass of muscles including the sternocleidomastoid. Anyone who has butchered an animal can testify to how difficult it is to cut through that muscle in a single blow even with the leverage provided by a fixed blade cleaning knife. The actual area that the vessels are superficially exposed is roughly the area of a quarter and is just below the jawline, so it is far more likely that a vertically thrown star would run into the jaw rather than penetrate the neck. The forward temporal region of the skull is quite thin and it is possible that a thrown star could penetrate, but again it is a small region (about the area of a half dollar) surrounded by much thicker bone, and even a full penetration is no assurance of death; the number of people who have survived shooting themselves through the temple (sometimes with little or no actual functional impairment) is legend. A strike to the back of the neck at the base below the occipital may be more incapacitating, but again, there is a lot of muscle there, and below the occipital region of the skull the spinal cord is pretty well protected by the spinal column; you’d need to be very lucky to go between the bones.

So, you’d have to be very, very lucky to kill someone with a “ninja throwing star”, and even a thrown knife or traditional shuriken is far from assured. A tomahawk, on the other hand, has enough momentum to penetrate deeply and with training can be thrown with good enough precision and force to cut into the chest cavity, penetrating a lung, which will slow anyone down.

I can penetrate watermelon skin with my fingernail, and punch straight though one with a closed fist. (I’ve seen people penetrate through the skin with an index finger strike but I’ve never conditioned my hands to withstand that kind of force.) Shooting, stabbing, and otherwise mutilating fruits and vegetables is a visually impressive trick but it is nothing doing damage through the surprising strength and resilience of human epidermis, fascia, and muscular tissue.


I suppose if you’re really, really lucky, you might get one right between two ribs. Definitely not something you’d want to count on, though.

The biggest risk is probably from tetanus, though that won’t kill quickly.

It could technically kill you, but that was never its intention (the chances of doing so are so low that it would be a pointless weapon it that was its primary purpose). They were intended to distract the opponent to make fighting them easier (having a metal star stuck in your face tends to be quite a distraction, particularly if it is in your eye).

And even just ducking out of the way so it doesn’t hit you might well be all the attacker needs.

That’s not going to kill or disable anyone. The amount of momentum you can get into a throwing star is not going to penetrate more than a couple of inches into the chest at most. It takes a surprising amount of force to push even a thin, dagger-like blade into the chest (and even more to pull it out against suction). That’s why bayonets are affixed to rifles; it would be more flexible and maneuverable to teach infantrymen to use a large stabbing knife or a gladius-type short sword than the awkwardness of rifle-mounted bayonet, but the weight of the rifle helps to push the bayonet into the target. (It does offer some modest amount of reach as well, but they way bayoneted rifles are carried and used negates most of that advantage.)


I thought the idea behind a bayonet was that you wouldn’t have to drop your primary weapon to draw the blade: You’re always holding both.

Well, the real idea of a bayonet is that you can form an infantry square to ward off cavalry charges without relying on a separate pike formation.

Being attached to a rifle doesn’t provide any significant advantage in helping push a bayonet into the target. A 75kg man pushing with all his weight won’t be helped much by the addition of a 3kg rifle.

Bayonets today are affixed to rifles mostly because a spear, even a poorly balanced one, is a much more effective weapon than a knife. A spear gives a reach advantage, which is important in itself. All things being equal someone with a bayonette will kill someone with a knife before the person with the knife has a chance to get close enough to do anything. This is even more true in massed charge. The reach of a bayonette also allows a soldier to attack someone hiding in a hole or behind a rock without having to leap into the hole with them. The reach advantage also has a massive psychological advantage for poorly trained troops. A spear also allows far more options: basically spear will do whatever a knife will do and also a lot more. Bayonettes are also much more effective at taking advantage of co-ordinated charges. A wall of advancing spears allows each person to attack anyone trying to attack fellow soldiers more effectively than knives. Of course the other great reason for using bayonettes is because a soldier doesn’t have to drop their rifle to fight. throwing away your rifle is frowned on in a modern army, and trying to fight with it tied to the back is impractical.

That was certainly the original idea. Hasn’t really been used that way for 150 years.

The problem with that is that when a fixed bayonet is stabbed into a body often gets stuck (either by suction or getting wedged between ribs) depriving the infantryman of his primary weapon if he can’t break off the blade. For this reason, infantry started using entrenching tools or just using the unfixed blade as a close quarters combat weapon rather than mounting it on the rifle. Despite the fact that military rifles are still made with bayonet lugs (and a tool referred to as a “bayonet” although bearing more resemblance to a straight-bladed utility knife rather than a traditional bayonet), they are essentially as obsolete as cavalry swords since the advent of military repeating rifles.


Right, but their subsequent uses have arisen almost entirely out of secondary uses they turned out to be reasonably good at. Without the need to replace pikes I’m not sure they would ever have been invented. Swords were the traditional backup weapon of early musketeers, not spears, and I suspect without the need for spears that the backup swords would simply have shrunk as firearm lethality increased without ever being strapped on to the end of the firearms.

And I wouldn’t want to be downrange of Oddjob with one of those either.

The rifle acts as both a brace, and the heft of the rifle gives additional resistance that is in the thrust line. Try this experiment; take a fixed-blade knife by itself and thrust it into a sandbag, then firmly affix it to a heavy pipe and do the same thing; you will get greater penetration and more control with the pipe, because of the additional leverage and momentum it provides.

Although the original theory beyond bayonets is that they would be used like the pike that was common with infantry when the first muskets were introduced, they really don’t balance or handle the way a long spear does. Because of the mass of the rifle it can’t be held out well in front of the infantryman the way a pike can, and the awkwardness of a rifle makes it a poor weapon for parrying an incoming bayonet or spear. As both rifles and bayonets have become shorter, the advantage of reach over a short spear or sword, both of which are more maneuverable, as essentially disappeared.

The reality is that even in the heyday of long-bladed bayonets mounted to long-barreled muskets, bayonet charges resulted in relatively few casualties in battle, and often posed as much hazard to the user’s fellow soldiers as to the enemy. With the advent of easily loaded brass cartridge-firing repeating firearms and rifled barrels with much greater accuracy, the utility of close quarters weapons by general infantry (and the infantry charge in general) has all but disappeared, and most troops use the bayonet as a general tool or as a harassment weapon rather than having any real combat utility. On the other hand, special forces and anti-terrorist units have come to recognize the value of a long-bladed offensive stabbing weapon for CQB use that is essentially a variation on the Roman gladius as a secondary weapon or in situations where firearms may pose a hazard. Such a weapon, with extensive training, can be quite lethal while the primary weapon is slung or holstered, or in the weak hand to prevent an opponent from grabbing the primary weapon in close quarters.


Going back to throwing stars: a lot of the analysis here is focusing on cheesy action-movie versions with six to eight blades, but if you look at the history of shuriken, you see:

  1. the name applies to a thrown dart or even a shape a Westerner would call a throwing knife.
  2. even among star-shaped ones, many have only three or four points

Wikipedia shows this collection of stars from a Japanese museum:
Some of those designs are quite capable of being lethal in the right circumstance.

Of course, there’s a notable lack of cheap stainless novelty stars in the museum’s collection. Those designs won’t kill anyone; they were never intended to do more than look pretty.

The homemade stars I saw in the 1970’s were made from steel plate had some weight to them and would must likely pierce a skull .