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 tallish man with a feminine appearance. He has his petrification scar running across his face.
When in battle, he wears armor which covers most of his body along with his head. 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 of 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 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 calls him out on wanting to murder the alleged science leader of the opposing team, he silences her by 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.
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.
- 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 also judged the velocity and distance for 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 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 in the military where he served as a soldier.
He was with Xeno when the petrification happened.
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.