The Professor

The Doctor (ドク, Doku) was a character in the Hellsing series and a member of the Millennium forces. His Japanese seiyu is Hiroshi Naka and his voice actor is Marcelo Tubert in the English dub. He is very loyal to The Major and the genius behind many of Millennium's projects, including his role in creating and training Millennium's many artificial vampires.

Appearance
The Doctor usually appeared dressed in a perpetually bloodstained white lab coat, an unusual shirt which reveals his lower torso, and glasses with an assortment of adjustable, multi-lensed spectacles. He wore four fingered gloves with both his ring finger and pinky forced into the last one. This suggests he may have had Syndactyly, having his last two fingers fused together on each hand. In moments of extreme tension, he tended to bite down one of his fingers, hard enough to draw blood. This is a disorder known as dermatophagia.

Powers and Abilities
He was Millennium's top scientist of physiology and technology, the genius behind many of their projects. Perhaps unstable, certainly eccentric, but undeniably brilliant, it was his research that led to the creation of a Nazi vampire army out of 1,000 volunteers in the 'Letzte Battalion'. Hirano has stated that he created Schrödinger, which goes well with his 'mad scientist' reputation. The two argue almost constantly, emulating a sort of father/son relationship. He appeared in the manga and OVA series, and as a silhouette to the right of the Major in the promotional video (found on the first DVD of the English release). It is possible that the Doctor created the Major's cyborg body, but it is currently unknown as to whether he is also a cyborg or something else, given how he did not appear to age visibly between the events of Hellsing: The Dawn and the manga series proper.

Plot
He was first seen in the museum alongside the Major watching Integra Hellsing and Enrico Maxwell discuss Millennium or as he said "Putting it together". He is seen again with the Major and also The Captain. The three of them were witnessing Alucard's fight with Tubalcain Alhambra in Rio de Janeiro, where he nervously bites his finger upon being forced to destroy him to salvage Millennium's secrets from falling into Alucard's hands. As the developer of the vampire conversion protocols, he joined the Letztes Bataillon in their assault to London, and in the same capability he converted Walter into an artificial vampire; despite his misgivings on the rushed, flawed operation, the Major green-lit Walter's intervention against Alucard. Based on Chapter 93 that The Doctor was going to release "She", the enigmatic, heavily bandaged figure from Hellsing: The Dawn, but had no idea of what to do.

At the end in chapter 94, cornered in the Deus Ex Machina, trapped, alone and desperately trying to salvage his research, he was arguing with Walter about how useless he (Walter) was and how he had become nothing but a failed experiment, and that one day he (the Doctor) would overthrow and defeat Alucard, and extend the progress his research embodied across all the world. He tried to press a button from his remote to kill Walter; however, Walter used his wires to cut off Doc's arm and leg, making him fall to the ground. As he fell, he ripped the blanket off SHE, revealing the ruined skeleton of Mina Harker, who Alucard, as Dracula, had forced to drink his blood.

Doc had, years after Mina's death, exhumed her body and used it to start his experiments in creating artificial vampires, hoping that one day Millennium would be able to defeat Alucard (or as Walter said "trying to imitate him"); decrying Doc's experiments as mere parodies of Alucard, Walter kept taunting the Doctor. Not long after that revelation, Doc was buried under a large heap of falling debris, killing him instantly. Later, his glasses along with the other items of people who died, were seen.

The Major
The Doctor greatly respects his boss and is one of the few who truly understands him. The Doctor fears The Major and often frets about his works, but The Major is all the same impressed by his talents and ingenious works. At first fearful as seen in The Dawn, the relationship between the two develop and The Major became The Doctor's closest friend over the next several decades when they and the battalion escaped from Germany. During the conclusion of WW2, The Major was shot and beaten up in a fruitless defense against The Soviets in Berlin and was rescued by The Doctor, who is implied to have also given his boss his cyborg body. The Major never underestimates him and the two share a lust for war, bloodshed, and violence. However, unlike The Major and most of the Millennium members, Doc planned to live rather than seek death and believes his work will benefit humanity in contrast to his boss's wish for an absolute war. He teases The Major when he misses all 8 shots when attempting to execute a German Navy ally for insubordination and the two share the same sense of humor. He was also genuinely very concerned for The Major when he stood on top of the zeppelin commanding the army as his boss was putting himself in great danger, telling him to come back inside. He essentially became mortified when an Iscariot helicopter was about to shoot his boss with a mounted rocket launcher, begging him to get back inside the zeppelin's safety while dodging scraps of metal before a rejuvenated Walter saved the situation.

Schrödinger
As stated by Kouta Hirano, Schrödinger was created by The Doctor and the two share a father-son relationship. He and the cat boy constantly argue with one another and emulates a mad scientist reputation. As they both enjoy war and excitedly anticipated for Walter and Alucard to fight near the end of the series, the two have much in common. The two watch in glee at the violence of London on top of The Major's zeppelin as their boss commands the Last Battalion as if it were an orchestra.

Walter
Upon first meeting Walter in Hellsing: The Dawn, he was dubbed as an enemy by The Doctor. However, upon Walter becoming a double agent for Millennium, The Doctor was fine working with Walter in secret. This is shown when The Doctor implanted a bomb in the Jackal that Walter would later give to Alucard as well as The Doctor turning the former into an artificial vampire despite the rushed process. As the Deus Ex Machina was falling apart, The Doctor argued with a wounded Walter with the latter saying his works (the Doctor) were useless and his life was a farce. This infuriated The Doctor saying that Walter was, to him, nothing more than a weapon for his superiors and that The Doctor will surpass She. Before The Doctor could kill Walter with a remote, Walter dismembered him and after explaining Mina Harker's origins buried him under rubble, killing him instantly.

Trivia

 * The Prototype for Doc is featured in Doc's Story
 * From his name-tag shown in Volume 3, his name appears to be Avondale Napyeer and is used as such by the Hellsing fanbase. The name-tag is difficult to read, however, and no official name has been given thus far.
 * Unlike most of Millennium's members, Doc planned to live rather than seek death like the others.
 * Unlike The Major who only seeks absolute war, Doc stated that he believes his work will benefit humanity.
 * According to the Major in The Dawn, the Doctor is a excellent saucet.
 * He could be based on Josef Mengele, a similar sadist Nazi scientist.
 * Furthermore, the fact he, (along with the rest of Millenium) escaped to Brazil to continue his research may be based off a consipiracy theory surround Josef of the same nature.