Demon Slayer (Kimetsu no Yaiba) is dominated by male characters. It would be interesting to rank which are the strongest as each character showcases different abilities and comes from a different race.
Demons have overpowered a lot of humans. Even Hashiras were eaten and easily defeated, especially by the upper ranks. Here is a list of the 20 strongest male characters in Demon Slayer.
#20 – Enmu

One of the strongest, able to manipulate the whole train. He was given more blood by Muzan so he would be stronger and will be able to complete the task of getting rid of some demon slayers and maybe a Hashira.
While he could not eliminate the Hashira or the other three demon slayers, he could still make several people disappear before the Mugen Train Arc.
#19 – Inosuke Hashibira

He may not be in the same league as the Hashira, but he was able to fight some of the strongest demons of his generation. He was able to see the faces of a few of the Upper Moons and survived. This is rare as some Hashira had not even met any of them.
These demons he came face to face with had bragged about having eaten Hashiras. To be able to fight them and survive would surely make you among the league of the strongest character.
#18 – Zenitsu Agatsuma

He only mastered one form of the Thunder Breathing style and used it in every battle, and he was able to fight toe-to-toe with these demons and survive something of a feat. Although he looks cowardly, he can stand up for others when the need arises.
Being able to face head-on the man who was the reason why the man who took you in when you became an orphan shows not only physical strength but emotional maturity as well.
#17 – Sakonji Urokodaki

He is capable of imprisoning a strong demon that would later haunt the Final Selection Exam grounds and would kill several of his students. Sakonji is one of the strongest Hashira in his generation.
Having mentored two of the strongest members of the Corps in the current generation is a testament to what he can do. He can create traps, run the mountains and walk for miles, even at his age. His swordsmanship is said to be legendary.
#16 – Gyokko

Being one of the upper ranks means that he is an exceptional demon. This was shown in his abilities and skills as he fought Hashiras and demon slayers in the village. He can teleport from one pot to the other and summon sea creatures like demons, each with different abilities.
Being able to manipulate multiple creatures with different abilities requires not only power but an excellent strategy. Gyokko has one of the most powerful Bloods Demon Art, which is key to how he became one of Muzan’s top lackeys.
#15 – Hantengu
He can make clones of himself that have the same power as himself. So fighting him would seem like you are fighting four Upper Moon. For someone to create a clone and be able to equally distribute such frightening power only shows just how much power they have.
He was able to frighten the village and face the members of the Demon Slayer Corps simultaneously.
#14 – Gyutaro

The demon is unfazed by the fact that he is facing a Hashira and other members of the Corps. He even bragged about eating 15 Hashiras in the past. This is no surprise, as his attacks were strong enough to cut the arms of a Hashira and stop all his attacks.
While attacking members of the Corps, he can watch out for his sister. He and his sister also ruled the Red Light District for years. He started as a nobody and ultimately became one of the strongest demons.
#13 – Tanjiro Kamado
He is in his own league but is still not as strong as the other Hashira. Despite being the wielder of two breathing style, Water and Sun, his strength and endurance is still not at par with his Hashira colleagues. His swordsmanship is one of the finest in the Corps.
He can easily smell the demon, and he was the only one among the Corps who had met Muzan in person and could identify him even in the middle of the crowd. As one of the newest members of the Corps, while he has strength, he is still growing.
#12 – Tengen Uzui

He can be flamboyant, but this man can wield dual Nichirin Cleavers with ease. Despite being poisoned by the demon, he was still able to face it head-on. He was able to easily cut off the head of Daki and shred her obi to pieces.
He has extraordinary strength, stamina, and endurance that is fitting for a former shinobi. He was also using his shinobi skill to continue fighting the demons.
#11 – Kyojuro Renguko

Fighting two Kizukis in one night requires extraordinary strength, stamina, and endurance. Kyojuro came from a long line of Flame Hashira. Disciplined, law-abiding, and cheerful, but let this not fool you, as this Hashira can easily break the neck of a demon.
His swordsmanship was shown in the Mugen Train Arc. He was able to fight the Upper Moon 3 and was even able to compete with his speed and strength.
#10 – Obanai Iguro

The Snake Hashira can fight the strongest demon with only one eye. He is blind in his right eye. Despite his handicap, he could rise to the rank of Hashira and fight demons. He has a small stature but exudes extraordinary strength.
He, alongside Tanjiro, pushed Muzan to the corner and showed how much stamina and endurance he had. He also survived the direct attacks from Muzan twice.
#9 – Muichiro Tokito

Muichiro was the youngest Hashira, yet it is a fact that he is one of the strongest. He was only 11 when he joined the Demon Slayer Corps and rose to become a Hashira in only two months after joining. His swordsmanship is one of a kind.
He could face two of the Upper Moons and their puppets and clones and hold them off until another Hashira arrived. He was able to continue fighting despite being poisoned. His small stature could withstand two demons that had existed for a long time.
#8 – Giyu Tomioka

Giyu is the epitome of calm. Being able to calm down and think even in the most difficult situation is his special skill. Add his swordsmanship to that, making him one of the strongest characters. Giyu can showcase how his swordsmanship was able to excel in different ways.
From fighting demons and having sparred with his fellow Hashira, how he used his swordsmanship when he fought different types of opponents shows his excellent skills.
#7 – Sanemi Shinazugawa

His marechi blood, which can make demons drowsy so he can easily defeat them, is not the only reason he is strong. Sanemi is one of the finest swordsmen in the entire organization. He was even praised by Kokushibo when they fought. Being praised by the second-best swordsman in his generation, if not in the history of Demon Slayer, means you have extraordinary skills.
This is obvious as he can face Kokushibo head-on in their fight, and they can push him into the corner and defeat him.
#6 – Gyomei Himejima

The strongest Hashira and their leader. Gyomei was able to beat a demon with his bare hands when he was younger, and that is when he discovered how strong he was. It is no surprise that the gentle Stone Hashira can easily defeat demons.
He was able to hold off Kokushibo and push him to the corner. In the final battle against Muzan, he also used the last ounce of his strength to ensure that Muzan would see the light of day.
#5 – Akaza

Akaza does not need any weapon to fight. He is a skilled martial artist when he was still human. He easily killed 67 kendo masters and mutilated their bodies. Even Muzan was impressed that he made him one of his top dogs.
Akaza is also the most trusted lackey of Muzan. Entrusted only with the most important mission. He can easily fight a Hashira using only his bare hands, and he becomes better the longer the fight is. He is an intelligent fighter who adjusts to his opponent’s fighting style and defeats them.
#4 – Doma

Another demon who would show no mercy. Doma’s attacks would get better the longer he engaged with his opponent. He is skilled in martial arts and with Blood Demon Art, and that makes him more deadly.
His body could adjust to Shinobu’s poison that would weaken ordinary demons. Doma is far from ordinary. If he had not taken a massive amount of poison by absorbing Shinobu, the other demon slayers would have had a hard time killing him.
#3 – Kokushibo

Kokushibo, even when he was still human, only came second to his twin brother. He is the second strongest among demons and the strongest lackey of Muzan. It took four demon slayers, three Hashira, and a lower-rank demon slayer, to take him down.
He was responsible for killing all Sun Breathing-style users and assassinating the Oyakata after becoming a demon. He was already skilled when human; he could even awaken his Demon Slayer mark. As a demon, he is vicious.
#2 – Yoriichi Tsugikuni

This man had traumatized Muzan, the strongest of all demons, for 400 years. For someone who leaves an impression and is still remembered and feared 400 years after his death only means that he is one of the strongest.
Not only is he physically strong, but he is also smart to create the breathing styles that we’re able to help demon slayers in defeating demons. He faces his brother at 80 years old, already blind, and almost killed the second strongest demon, Kokushibo.
#1 – Muzan Kibutsuji

The demon who started it all. Having lived for more than 10,000 years and still terrorizing the whole world. Muzan was never defeated. None among the demon slayer could catch up to how fast he could regenerate. He is a demon who can create more demons and control them.
Imagine being feared by demons themselves. He is revered both as a god and a punisher among demons. He is worshipped and feared by all. Even the strongest demon slayers know that killing him would be near impossible.