The Convention of Twelve
A secret organization that controls England from the shadows, and is modeled after the Knights of the Round Table. Some members of Parliament, military officers, and a few prominent nobles are among its members, as well as the leader of Hellsing (currently Integra). Integra's father and predecessor Arthur Hellsing (who gets some screentime in Dawn) may have been the "leader" of the Convention, and passed his position of authority to his daughter and Sir Islands. It is likely that membership is hereditary; Sir Penwood informs Integra that this is how he got into the Convention, and the finale reveals that Sir Penwood's grandson succeeded him.
- Sir Hugh Irons/Islands voiced by: Katsunosuke Hori (Japanese), Doug Stone (English)Sir Shelby M. Penwood voiced by: Masashi Hirose (Japanese), Stuart MacLean (English)Lieutenant-General Rob Walsh voiced by: Ryuzaboro Otomo (Japanese), Orion Acaba (English)
- Badass Bureaucrat: The Convention of Twelve do not take Jan Valentine lying down, instead shooting him en masse the moment he opens the door. In various occasions they stand their ground against suped up Nazi vampires.
- Badass Family: The Hellsings. They've been in the vampire killing business for years, with van Helsing as their ancestor and keeping the original vampire sealed up in their basement for god knows how long.
- Subverted by Richard Hellsing, who tried to kill Integra to inherit the Hellsing estate.
- Cool Hat: Sir Islands wears a top hat. Sir Walsh has a snazzy beret.
- Cowardly Lion: Sir Penwood admits that he's no fighter, a nervous man who was given his position by being born into it. But when Millennium attacks London, he insists on staying and defending the Command Centre because that's his job as commanding officer, even going so far as to order his crew to leave him.
- Heroic Sacrifice: Sir Penwood blows up the entire Command Centre to take out a chunk of Nazi officers, including himself.
- Heroic Self-Deprecation: Sir Penwood's admission of how nervous he can be and that he's only in his position out of obligation.
- Mauve Shirt: What makes Sir Penwood stand out from being a Red Shirt is how he explains why he knows he's not suited for the position he's in but he's going to make a stand. Even after his death he still makes an impact on the aftermath.
- No Name Given: The majority of them are not known. Just Sir Islands, Lieutenant-General Rob Walsh and Sir Shelby M. Penwood (and, of course, Sir Integra).
- Reasonable Authority Figure: None of them are ever depicted as unreasonable in their orders and understanding of the situation.
- Spell My Name with an "S": Sir Islands or Sir Irons?
- The Stoic: Present-day Sir Islands, who never cracks or shows any emotion whatsoever.
- Taking You with Me: Sir Penwood blowing up the Command Centre with him and Nazi vampires in it.
- Technical Pacifist: Sir Islands's descendant wants to solve conflicts without weapons, in the epilogue.
- The Mentor: Sir Islands to Integra, as far as is shown. She certainly looks to him for advice as opposed to the others.
- The Omniscient Council of Vagueness: From an outsider's perspective, it's never explained why the Convention is so important to the running of England, apart from a vague implication that they do damage control for supernatural events such as vampire attacks.