!Zwei/Reiji Azuma
->Voiced by: Kousuke Okano (Japanese, visual novel), Creator/TakahiroSakurai (Japanese, OVA), Creator/MiyuIrino (Japanese, TV anime), Creator/KeithSilverstein (English, OVA), Newton Pittman (English, TV anime)
* AntiHero: Though he is fully aware of the consequences and misdeeds of his actions.
* BadassInANiceSuit: During his time as an assassin he's commonly dressed in finely-tailored dark suits.
* BadBadActing: A rare funny moment comes in episode 4 when, after Ein and Zwei spend a day posing as vacationing sweethearts while scouting out their next target, she has this to say about his atempts to act casual:
-->'''Ein''': "Hey Zwei?" ([[{{Beat}} long pause]]) "Your acting... [[TheComicallySerious stinks]]."
* MyGodWhatHaveIDone:
** After he accidentally [[spoiler:shoots Ein while trying to kill Scythe Master]]. Made even worse by the fact that [[spoiler:the entire time he was trying to SAVE HER LIFE.]] And lets not forget those flashbacks we get to when [[spoiler:they're trying to escape]] and he promises that, one day, he'll make her laugh again.
** Zwei gets this AGAIN after realizing, that it's his fault [[spoiler: Cal got into being an assassin]].

->Voiced by: Creator/OmiMinami (Japanese, visual novel & OVA), Creator/AyahiTakagaki (Japanese, TV anime), Creator/MelaLee (English, OVA), Creator/LindsaySeidel (English, TV anime)
* {{Brainwashed}}: Scythe does this to her to keep her loyal. [[spoiler:After Claudia's coup d'etat, the process is ceased and reversed on the agents they still have. Scythe himself later decides that ''[[NotBrainwashed not]]'' brainwashing his subordinates may actually make them stronger.]]
%%* EmotionlessGirl
* InnocentFanserviceGirl: Ein doesn't care about walking around naked in front of Zwei after having a shower.
* SexyBacklessOutfit: Ein's party costume in episode 6 and the dresses of the Zahlen Schwestern, both in the recent anime and in the visual novel.

!Cal Devens/Drei
->Voiced by: Creator/SatomiKoorogi (Japanese, visual novel), Creator/MiyukiSawashiro (Japanese, TV anime), Creator/BrittneyKarbowski (English, TV anime)
* CorruptTheCutie: Scythe seperates her from Reiji and manipulates her into hating him, turning her into the new Phantom.
* DyingAsYourself: After Scythe brainwashes her into giving into her hatred and becoming a remorseless assassin, Reiji fatally shooting her brings her back to her senses and she dies remembering her time with him fondly.
* ShesAllGrownUp: After the two-year time skip she becomes quite well-developed, a notable jump from her previous, childish appearance.

!Claudia [=McCunnen=]
->Voiced by: Creator/KikukoInoue (Japanese, visual novel & OVA), Creator/AyaHisakawa (Japanese, TV anime), Creator/CindyRobinson (English, OVA), Creator/ColleenClinkenbeard (English, TV anime)

!Mio Fujieda
->Voiced by: Creator/AmiKoshimizu (Japanese, TV anime), Creator/LeahClark (English, TV anime)

!Scythe Master
->Voiced by: Creator/KenNarita (Japanese, visual novel), Kazuhiro Nakata (Japanese, OVA), Creator/IsshinChiba (Japanese, TV anime), Dave Mallow (English, OVA), Creator/KentWilliams (English, TV anime)
* DubNameChange: The English Dub of the OVA switches his name around, changing it to "Master Scythe."
* FourEyesZeroSoul: The TV series and subsequent remake gave him glasses.
%%* MadScientist
* NonActionBigBad: Despite overseeing and monopolizing on the creation of assassins, Scythe Master himself has no combat skills and relies on his minions even in [[spoiler:his final showdown with Ein]], where he even throws away his own weapon instead of trying to fight her.

!Lizzie Garland
->Voiced by: Creator/AiOrikasa (Japanese, visual novel & OVA), Creator/AkenoWatanabe (Japanese, TV anime), Creator/MeganHollingshead (English, OVA), Shay Moore (English, TV anime)
* AdaptationalAttractiveness: In the [=PS2=] game and OVA, she almost looks like a dude. However in the 2009 series, she is much more attractive looking.