The Millennium Group

Names: Major, Montana Max, mistakenly called Major Krieg (after misinterpretation of his calls to War during V4.)
Age (in 1997): Unknown, assumed ~82 (if 30 in 1945.)
Weapons: Small gun attached secretly to his chair, the Millennium legion/Million Man March.
Status: Leader of Millennium, second to the late Führer in regards to the occult research.
Power: Unknown, though it's suspected he can manipulate the mind's of others in some sort of 'voodoo.'
Relationships: Integral (rival,) Alucard (opoonant.)
Bio: The Major was despised during the war, even afterwards, for his short stature and eerie smile. He commanded the research into vampirism and later instigated the attacks on Hellsing. He seeks only to live for war eternally, whether it be at his loss or victory.

Bonus!: The Major's first appearance is in Hirano's old comic series, "Coyote," where he's MUCH thinner, almost twig-like.

Names: The Doc, Doktor, Dok.
Age (in 1997): Unknown, assumed ~90 (if 40 in 1945.)
Weapons: A button that lights particular subordinates on fire from the inside.
Status: Researcher and scientist.
Power: Unknown, if any at all.
Relationships: Major (advisor,) Schrödinger (griefer.)
Bio: The Doc is known to have been researching vampires and their effects on humans (POWs) during WWII, but after The Dawn, it's unknown what influences he had. Within the fandom, it's assumed that he's the one who turned everyone in Millennium into vampires, and installed the transmitter chips inside most (if not all) of its members, which is used to moniter the target and transmit what they hear. The chip can also be detonated and set the victim on fire. According to Kouta Hirano, the Doc created Schrodinger, as well. Beyond that, the Doc is a meak associate of the Major's and consults to him about the status of the soldiers and many other things.

Bonus!: Doc's origins trace back to a one-shot hentai of Hirano's wherein the Doc, clad in a full Nazi uniform instead of his lab attire, bears witness to a rather absurdly comical scene where Hitler is having sex with a buxom cat-girl associate. Fans sometimes muse that this is where Schrodinger came from, but aren't serious.

Names: Captain, Hans Günsche, Cap
Age (in 1997): Entirely Unknown
Weapons: Extra-long mauser, knife.
Status: Major's bodyguard.
Power: Can turn into a werewolf (which is why his age is completely unknown,) extreme speed, high pain tolerance, regeneration.
Relationships: Major (bodyguard and escort.)
Bio: How the Captain came to be in Millennium is completely unknown, as is his reasons for remaining with them and obeying the Major. He was Walter's rival in The Dawn and has cntinued that tradition through to 1997 when he confronted Walter again in Volume 6. The Captain has never spoken a single word, even before Walter's wires slashed his throat in 1945.

Bonus!: Captain was supposedly a character in a relatively unknown comic called "Desert Schutzstaffel." It's possible this is where the name Hans Gunsche came from.

Names: Rip Van Winkle, der Freischutz/the Sharpshooter, Kaspar
Age (in 1997): Unknown, assumed ~72 (if 25 in 1945.)
Weapons: Elongated old-world musket.
Status: First Lieutenant.
Power: She commands the renouned Magic Bullet, which she can control apparently at will.
Relationships: Alucard (Samiel,) Major (2nd in command/Naval commander.)
Bio: Rip has long been in Millennium, fighting Alucard (or his coffin anyway) even as a human. She lives her life as if the living embodiment of Der Freischutz's main character, Kaspar, who is given magic bullets by the Devil of the Hunt, Samiel. Because of this allusion, many fans toy with the idea that it was Alucard (who is Rip's Samiel) that gave her the ability to use her gun as she does, though her presumed humanity in 1945 makes this assumption difficult to substantiate. Alucard clearly remembers Rip in 1997 though on the Eagle because of his brief encounter with her in 1945, though how he knows her name is unknown since she never quite introduced herself. Perhaps he learned it after devouring Tubalcain, when he also learned of the Major.

Names: Tubalcain Alhambra, Dandy Man.
Age (in 1997): Entirely Unknown.
Weapons: Playing cards.
Status: Lieutenant.
Power: Increased speed, can morph his body into playing cards and reform himself, throws cards like knives..
Relationships: Major (4th in command.)
Bio: It's up in the air how Tubalcain came to Millennium, but it can be assumed that he was picked up after Millennium fled to South America. He is the second of the group's forces to assault Alucard and is the first to completely reveal who and what Millennium is.

Names: Zorin Blitz, Joleen, Zooling.
Age (in 1997): Entirely Unknown.
Weapons: Scythe.
Status: Captain.
Power: Can weave illusions based on the most raw of her victim's memories.
Relationships: Major (3rd in command.)
Bio: Zorin's status in Millennium has only briefly been mentioned, though she is given command of one of the Graffzeppelins and the task of guarding the Hellsing manor until the rest of Millennium's forces arrive to tackle Seras there. She, however, got cocky and attacked against orders. As such, she was given no help from the rest of the group, and taunted by Schrödinger upon her death.

Names: Schrödinger
Age (in 1997): Unknown, assumed ~50 (if created after Millennium's retreat to Brazil.)
Weapons: None.
Status: Warrent Officer, Messenger, Envoy, cat boy.
Power: Omnipresence.
Relationships: Major (envoy.)
Bio: Schrö was supposedly created by the Doc at some point, though it's unclear what reasons he might've had for doing so. Either way, Schrödinger's ability to be "everywhere and nowhere" is certainly useful to the Major. Schrödinger thusly present personally at both Rip Van Winkle and Zorin's deaths, showing the Major how it occured through his two-way video panel. Schrödinger's being a cat boy, and being created by the Doc, was substantiated by Hirano himself at AnimeExpo 2005.