Stanley Snyder is an ex-military officer currently working for Dr. Xeno.
"The first to strike wins, y'know? I was hoping to crush you all... but now I've got a whole heap of questions."
— Stanley Snyder, Dr. Stone, Chapter 151
He is the secondary antagonist of the New America City Arc.
Stanley is a tall, well-built man with very feminine facial features. He has arched eyebrows and relaxed-looking, light colored eyes with what appears to be dark eyeliner underneath. Similarly, he has glossy, colored lips that suggests he may be wearing lipstick. His hair is of medium length and neatly slicked back, with a large strand falling in his face and the small area around his ears shaved short. His petrification scar runs horizontally across his face in a jagged line.
When in battle, he wears a large suit of armor which covers most of his body along with his head. The armor is extremely intricate, with large shoulder pads that are decorated with a feathery material hanging from the bottom of them that covers Stanley's body like a cape. The mask he wears with this armor is surrounded with similar material that hangs off his head, somewhat resembling a lion's mane.
Outside of battle however, he wears a dark bodysuit with gloves, a back holster, knee pads, and armored greaves that have spikes on the side of the soles. Even in this state, he also carries a large bolo knife in his belt and a pistol on his hip at all times. He is usually seen smoking a cigarette.
From what is seen about Stanley, he appears to be a "shoot first ask later" person. This was seen when he attacked the Kingdom of Science when they arrived, despite them doing nothing to warrant an attack. However, Xeno stated that was because Stanley wanted to elaborate to them the advanced skill of his benefactor, should they be hostile.
He does get amused when he finds something interesting, as seen when he was intrigued by the Kingdom of Science dodging his machine gun fire and bringing down his airplane.
Owing to his past as a soldier, Stanley is very observant of his opponents. He carefully inspected Senku's group as they hunted alligators to find out how much threat they pose to him and his allies. When he prepared to take Gen away, Stanley performed a pat down for weapons. Furthermore, Stanley sent Luna as a spy to draw out the science leader knowing full well that they would help someone in need and that they wouldn’t abandon an ally.
Dr. Xeno makes a scorning remark about his frequent habit of smoking, something the former has no problems with. Stanley has no qualms about endangering and potentially killing the intruders, regarding his previous assault on them merely as a show of power. When Luna called him out on wanting to murder the alleged science leader of the opposing team, he silenced her with a mere coldblooded glare.
Attesting to his extreme willpower to endure four millennia under the effects of petrification, Xeno doesn't doubt in the slightest that Stanley can complete a task once he sets his mind on it. Stanley himself even confirms this by stating no matter how hard the task is, he can get it done.
While he does seem to show strong loyslty to Dr. Xeno and faith in his abilities, he doesn't seem to hold his other allies in high regard. Of note, once he shot Senku, rather than retrieve Luna who was still enemies with the Kingdom of Science at the time, he chose to leave her there despite her status as a spy becoming known and showed no concern for her safety or even an attempt to rescue her in chapter 160.
Abilities and Skills
Combat proficiency: Judging from his background as well as his assault on Senku's group, Snyder is a valuable member of Dr. Xeno's group for his skill in modern warfare. At first glance, he could tell that Gen was not a developed fighter and that Senku's warrior group should be approached with caution.
- Skilled Strategist: He initially planned on wiping out the entirety of the ship crew with a decisive strike, only to lose his aircraft. Eventually, he took one of their members in for intel instead. To draw out the science leader, he sent Luna and told her to signal to him once she located him. Furthermore Stanley was able to identify his target after reducing the he would look at Luna and then in his direction. 
- Marksman: Stanley uses a variety of weapons such as a machine gun. While Stanley is skilled, he was unable to hit members of the Kingdom of Science but did graze Matsukaze in his shoulder. Stanley is also capable of judging the velocity and distance for a single sniper shot, by using the stripes on Luna's outfit.
- Mental Resilience: Among the select few mentally strong enough to withstand the millennia-long effects of the Petrification, Stanley possesses an extreme amount of determination. Immediately after Dr. Xeno suggests eliminating Taiju to bring down their adversaries, Stanley is set on the task. When inquired by Gen on how he can pull such a feat, he simply assures him he is capable of it without justification.
Stanley carries a machine gun on him. He also carries a pistol and a dagger on his side.
Prior to the Petrification, Stanley was childhood friends with Dr. Xeno. Later in his life, he was in the military where he served as a soldier and leader of an elite unit.
He was with Xeno when the Petrification happened and he was the first to spot the petrifying light, warning everyone and telling them to keep their consciousness.
After his revival, Stanley at some point became an employee of Dr. Xeno.
Stanley then killed a pack of wolves that were prepared to attack him. The Kingdom of Science then set up camp but many of the Warriors detected Stanley and alerted their allies, before Stanley used his machine gun to open fire. However, the Warriors were able to rescue their allies while Stanley was taking time to reload they took the opportunity to flee. Amused, Stanley was excited about the chance of hunting them down. 
Using his aircraft, Stanley pursued his enemies on the river and resume opening fire. However his plane was brought down by the actions of Senku Ishigami and Kirisame. Amused, Stanley abandon ship and contacted ask Dr. Xeno. After briefly talking about the situation, the two conferred with their enemies as a science user like him. 
Forced to take a tactical retreat, Stanley came across Gen Asagiri, who quickly surrendered when a weapon was pointed at him. Stanley proceeded to check Gen but found no weapons and realizes he is not one of the warriors he saw from before. Stanley questions who Gen before he learns the latter is magician and has Gen follow him. He tells him that he was planning to snuff out his allies sooner but now wants to interrogate Gen for what his colony is. Stanley leads Gen to the American base. Dr. Xeno is present in the fortress factory when Stanley brings Gen Asagiri in for questioning. Stanley says that it's no surprise to locate Dr. Xeno in his factory, as Gen is put onto something that looked like a polygraph test. Dr. Xeno introduced himself along with Stanley, before intently questioning Gen on who he is and where he came from. After the latter gives his name and some of his history, Xeno is fascinated to hear that the man comes from Japan, having taken to face the dangers of the stone world to reach America. After Gen describes his leader's behavior, Xeno makes a point that the stranger may either be honest to a fault or a very good liar. He doesn't mind however, saying that he is fond of both types while Stanley figures to eliminate the leader. At the end, he watches Xeno inquire on the lead scientist's name, to which Gen replies with "Dr. Taiju".
On the orders of his employer, Stanley uses his second plane to search for the Kingdom of Science, eventually finding the Perseus. From his position, he remarks on the size of the ship.
He goes to kill Taiju, who Gen tricked them into thinking is the leader of the Science Kingdom. Stanley is confident that he could handle the warriors.
He gathered a group of other survivors: Luna, Carlos, and Max. He explains his mistrust of Gen and explains his intentions of killing Dr. Taiju. After gathering a good vantage point, he catches a glimpse of the Perseus and why he needs Luna. He then sends Luna to spy on the Kingdom of Science to draw out the science user for him to snipe him.
Sometime later Stanley notice is Luna is on the deck where he notices her odd behavior. Stanley soon identifies “Dr. Taiju” and prepares to take the shot. Just as he is about to take the shot, Xeno contacts Stanley to tell him that the supposed science user is not the one you’re looking for but that of his old pupil Senku Ishigami, following Carlos contacted him. This shocks Stanley and he doesn’t take the shot. 
Dr. Xeno reiterates that Taiju is not the enemy scientist, but his former pupil Senku is. Stanley then asks Xeno to describe Senku. Xeno uses a recording of the Perseus’ transmissions. Stanley complains that he can’t hear their voices, but Xeno says that he’ll use Senku’s voice to calculate his height. Xeno estimates his height and his age. Stanley (using Luna as benchmark) narrows his targets down to three. When the crew catches wind of a sniper nearby, Stanley is irritated by this. Soon Luna looks in his direction Stanley briefly complains about this but then realizes that he can use this to us advantage as the enemy scientist would look into his direction given away his identity. Surely enough, Senku looks at him, as Stanley readies the shot. He is impressed by Senku ducking from Stanley’s line of sight quickly, though Stanley uses that information to predict where Senku will hide. Before taking the shot, Stanley asks Xeno whether or not he’s sure he wants Senku dead, which Xeno confirms, believing that Senku would never agree with Xeno’s ambitions and the shot is fired. 
Believing his mission to be done, Stanley tells Carlos and Max they can choose to abandon or rescue Luna either way his task is complete and he heads off. 
Stanley returns to the base, where he walks in on the conversation regarding the Petrification Weapon. He questioned Gen on how to use it, as the latter explains that it is capable of petrifying people.
After Dr. Xeno creates a submarine, Stanley and his unit attacked the Perseus wall having one of his soldiers act as a decoy in the other playing to distract the enemy. Once the aerial battle is over. Stanley ejects himself from the submarine, landing on the ship. He then proceeds to attacks Matsukaze and Mozu by using his pistol to destroy their weapons and injure their shoulder. Stanley reports to his leader that the enemies have been detained unaware that he has been captured.