Hellsing, like many anime, started as a manga series. Written by Kouta Hirano, the story revolves on an English organization called Hellsing, based on the original Van Helsing. It's mission is obvious; to hunt down vampires and other supernatural threats to England.
The first anime adaptation of the franchise was in the form of a 13 episode long television series from Gonzo Studio in 2001. The result was somewhat tame compared to the manga, and wound up moving past all of the material that Hirano had written approximately halfway through its 13 episodes. This meant that Gonzo was forced to fabricate their own ending which differed greatly from the manga. The series also suffered from uneven animation quality as a result of budget issues.
In 2006, a new adaptation of the manga was released, this time taking the form of an OVA series. Originally animated by Satelight Studios (parts 1 through 4) and now by Madhouse Studios (parts 5 and onward), the OVA titled Hellsing Ultimate features the same voice cast as the original series, but is a much closer adaptation of the manga than its predecessor and boasts a greatly improved budget, stricter animation quality control, and no censored material.
As both the television series and the OVA contain many of the same weapons, both are listed here. Weapons exclusive to one adaptation or another are noted as such.
The following weapons were used in the anime series Hellsing:
Alucard's signature weapon is the Hellsing Arms .454 Casull (unofficially known as the "Joshua"). This weapon is the first custom handgun made by Hellsing, and was specifically designed by Walter. It's essentially a very big semiautomatic pistol, with a length of 39cm. It's chambered for the mighty .454 Casull round, which finds use primarily in hunting large game, such as deer and bears. Of course, these bullets are special, being made out of silver obtained from melted holy relics, with an exploding property as well, making for a rather devastating cartridge against the legions of the night. The Casull is believed to be based upon the Colt 1911 (or its variants like the longslide), however it also bears a resemblance to early model Colt pistols. In some close ups, one may note that the hammer is never fully cocked, indicative of either a double action or fast-action mechanism similar to the Daewoo DP51. The lengthy barrel and slide gives this gun incredible accuracy, and the weight at the front of the gun makes the massive round significantly more controllable. Something this extreme suits Alucard perfectly.
Trivia: During the flashbacks to World War II (specifically 1945) seen in much of the OVA's promotional material, Alucard is seen using this same weapon. This is anachronistic, as the .454 Casull round was developed in 1957.
Jackal
Alucard's second handgun is the Jackal, which was also made especially for him. The Jackal was made by Walter after Alucard's first encounter with Anderson - in fact, it likely was specifically designed with him in mind, considering the phrase "'Jesus Christ is in Heaven Now'", a variation on a similar statement on Anderson's equipment, is engraved on the side. The Jackal has an overall length of 39cm (the same length as the Casull), is made from pure silver, and weighs 16kg. The slide covers the entire top frame, and there are thus no creases or lines on the top part of the gun, making room for the engraving. Obviously, no human could possibly use this gun without being blown away by it. The breech also faces the left, instead of the right, so it's more of a sister gun to the .454, though it's magazines can hold about the same amount of bullets that the Casull is capable of. The bullets are different as well, being a bigger 13mm, with a gold casing, a reinforced core for armor penetration, a mercury explosive and each bullet being baptized. Compared to the Casull, the Jackal is distinctly lacking in terms of aesthetic features, and is devoid of any contours on the side or frame save for the grip. This suggests that Walter designed the weapon immediately after Alucard's encounter with Anderson and did not have time to improve its appearance.
This gun is of fantastic proportions. No 13mm round was ever produced. A .50 alone would equal 12.7mm, meaning each bullet must be manufactured by Hellsing alone. It's curious as to how this weapon can weigh 16kg when a full size 7.62X51mm machine gun only weighs 11kg, the weight is probably necessary to control the 13mm rounds, though with a gun this heavy you could probably fire a .50cal BMG round and still have the same desired effect.
Heckler & Koch Mark 23
Seras's sidearm is a Heckler & Koch Mark 23 in the original television series. It was replaced by a more sensible P226 in the OVA.
SIG P226
A SIG-Sauer P226 is seen in the hands of Seras during her time as a police officer. Integra also uses a P226 as her sidearm as choice, stating that it is loaded with silver Heavy Explosive rounds.
Pip uses a Glock with a suppressor in the OVA. Seras also had a Glock as her sidearm when she joined Hellsing in the Anime. None of them can be seen clearly enough to distinguish the exact model/caliber.
Submachine Guns
Customized FN P90s
Yan Valentine wields a pair of heavily modified FN P90s. Both have part of the stock and handle removed, with a more conventional pistol grip placed instead. A silencer has been added, along with an underbarrel laser dot sight. Of course, his eye sigil also adorns the side of the weapon. In the TV series, one had a long scope attached to it and the other a red dot sight.
Heckler & Koch MP5A3
Both Hellsing members and London police officers are seen with H&K MP5A3s.
Heckler & Koch MP5K PDW
Yan Valentine's ghouls are all armed with H&K MP5K PDWs equipped with PVS-14 night vision scopes and suppressors. This same design was also seen in the hands of a few police officers.
Beretta PM12S
The Beretta PM12S was seen in OVA. It is possible that these are Taurus PM-12s (a licensed copy of the Beretta PM12S made in Brazil) since these are used by a Brazilian police SWAT team.
Skorpion SA Vz 61
One of the vampire teens in the TV series uses a Skorpion SA Vz 61. In the OVA, it was replaced with a Micro Uzi.
Micro Uzi
A Micro Uzi was see seen in the hands of a vampire teen in the OVA.
Uzi
A police officer can be seen wielding an Uzi during the first episode of the OVA.
MP40
The Millennium Organization's army of Nazi vampires are largely equipped with MP40s.
Steyr MPi81
A vampire steals a Steyr MPi81 from a police station in the TV series when he attempts to escape.
Thompson M1928
A M1928 Thompson can be seen in Alucard's dream sequence at the beginning of the 5th OVA. The entire dream revolves around films based on Frederick Forsyth novels. The Thompson is seen during a reference to The Fourth Protocol.
Rifles
Seras's Rifle (Hellsing Anti-Midians 13.7mm)
This unnamed rifle was used by Seras before she was given the Hallconnen. She also used it with a drum magazine later on in the TV series and OVA. In the original TV series, the rifle had a more black polymer finish and stock, but in the OVA, it was switched to wood. Also in the original TV series, this rifle was fully automatic, but in the OVA, Seras's only fires it in semi. This weapon is clearly manufactured by the Hellsing organization for anti-vampire combat, though it is uncertain who was intended to wield it before Seras joined. The stock engraving reads "Anti-Midians" and gives the caliber of the round as a massive 13.7mm.
Sawed-Off M1 Garands
Luke Valentine's weapon of choice is a pair of sawn-off M1 Garand rifles. In the television series, both the stock and barrel/fore-end have been cut down, effectively turning these rifles into high-caliber pistols. In the OVA, only the barrel and fore-end have been cut, and the stock has been left intact.
The M16A1 rifle is used by Hellsing forces in the original TV series.
M16A2 Rifle
Several M16A2 rifles are used by Brazilian solders/officers in an (unsuccessful) attempt to kill Anderson.
L85A1
Traitorous British soldiers in the OVA are seen wielding L85A1 service rifles. Another is seen in the hands of a member of the Wild Geese during Zorin's assault.
Norinco Type 84S
Two members of the Wild Geese in the OVA are armed with Norinco Type 84S rifles.
AK-74
Most of the Wild Geese in the OVA are armed with AK-74 rifles.
AKS-74U
Several members of the Wild Geese use AKS-74U rifles while working for the Hellsing Organization.
Sturmgewehr 44
Several of the Nazi vampires in the OVA are armed with Sturmgewehr 44s.
Both Seras and assorted Hellsing members use Accuracy International Arctic Warfare L96A1 sniper rifles. Seras was told to not equip hers with a scope because, as a vampire, she can see farther than any human could.
Heckler & Koch PSG-1
A H&K PSG-1 is used by a Brazilian police sniper team.
An Ithaca 37 "Stakeout" is stolen by a vampire as he tried to escape from a police station in the TV series.
Heavy weapons
Hallconnon cannon
Seras Victoria gets this cannon later in the series. This is the weapon that Walter gives Seras in episode 5, "Brotherhood" and the OVA shows the same scene as well, in the 2nd episode. This weapon's name is actually pronounced "Harkonnen" and is a reference to the primary antagonists of the novel Dune, House Harkonnen (the spelling discrepancy is the result of the Japanese pronunciation of "Harkonnen"). The cannon is almost hilariously oversized, but Seras soon handles it like a normal rifle because of her strength as a vampire. Walter says that it uses depleted uranium shells, and high explosive rounds. The Hallconnon fires 30mm cannon shells.
This is effectively an artillery piece scaled down to so a person can hold it like a rifle, which Seras does from time to time. It operates using a traditional breech-action system.
Incognito's Armscor 40mm MGL
This is a fictional multi-shot grenade launcher based off the South African Milkor MGL. The weapon does not fire normal explosive grenades (though a wide range of ammo can be used, Incognito loads them with special shells containing multiple dart-like objects that have some magical property, which Alucard describes it as "magic from the dark continent"). As with Incognito himself, this weapon only appears in the television series.
M202 FLASH
Luke Valentine uses a M202 FLASH to break into the Hellsing compound in the TV series.
Arwen 37
Seras uses an Arwen 37 grenade launcher several times in the TV series.
The Mk 47 Grenade Machine Gun is used by the Wild Geese to defend Hellsing manor against Millennium's forces with devastating effect.
Panzerfaust
Millennium's army of Nazi vampires in the OVA makes liberal use of a multitude of Panzerfaust launchers.
Panzerschreck
Several Nazi vampires carry Panzerschrecks during the attack on London.
CIWS
A CIWS Phalanx on the deck of the captured British aircraft carrier is used against Alucard's Blackbird in the OVA.
Hallconnon II
The Hallconnon II is a weapons system consisting of a pair 30mm semi-automatic cannons coupled with an incredibly large ammunition supply. Seras uses these weapons to barrage Zorin's blimp with an overwhelming display of firepower. The ammunition containers are detachable, and Seras is seen using Hallconnen II without them, though she quickly runs out of ammo.
Vladamir
Described as a "Wide area saturation, high explosive incendiary grenade launcher", the Vladamir is a set of muzzle-fired grenades that are part of the Hallconnon II weapon system. Seras uses these to deliver the final blow to Zorin's blimp.
Wall of Guns
Seen in the first episode of the OVA. It consists of
a Sig P220 series
an AK-74
an M16 with the three-pronged compensator [drawn upside down]
an M1911
an M16 with the birdcage compensator
a Colt Python
Franchi LM57
Sten MkII
Lee-Enfield No4 (With bayonet attached)
Near the end of the wall of guns several muzzle-loading muskets, one with a bayonet attached, can be seen.
And all these were pointed at Alucard, but were still not enough firepower to take down one of the most powerful vampires in existence.
There's also no one holding any of the guns.
Unknowns
A custom job possibly based on the South African Mamba 9mm??