Although starting out as a series of videos of the same scene, with Hitler ranting about whatever topic comes up, Hitler Rants has since evolved into a universe of its own with more scenes from Downfall and even other films being used. The character sheet for the original film is here.
Adaptational Villainy: In Downfall and in real life, Fegelein was only an assistant to Himmler and got shot for desertion upon trying to leave the bunker. In the internet videos, he's more of a Trickster making life in the bunker a living hell. The real life Fegelein did commit serious war crimes though.
Commander Contrarian: His only purpose is to object to whatever comes out of Hitler's mouth. Of course, the one plan he agreed to (getting a pay raise) was the plan Hitler actually wanted him to object to.
Deadpan Snarker: To the point that in more recent planning videos by hitlerrantsparodies' videos, Jodl throws all respect out the window and begins the video with "What kind of stupid plan are you planning now?"
Only Sane Man: Often the case, particularly when Hitler's schemes are on the verge of lunacy.
A psychotic demolitions expert from Ireland, Mallory bears a strong irrevocable grudge against Hitler for reasons unknown. Whatever it is, Mallory is determined to blow up Hitler by any means necessary, and will destroy anything else that may get in the way of his quest.
Breakout Character: Mallory was originally supposed to be a one shot character in HitchcokJohn's parody Duck, You Führer. After its success, he saw comedic potential in Mallory and decided to make him a recurring character.
Determinator: Nothing will stop Mallory from blowing up Hitler.
Foil: To Adolf Hitler himself- in contrast to the latter's ranting about mundane things, Willenbrock is much more level-headed and stays focused on the task at hand. Naturally he usually succeeds or at least finds ways to benefit from Hitler's misery.
The Quiet One: Werner actually has very little dialogue in the film, and most of the few lines he does have are pretty short. In-universe, it's implied that this is because he spends more time plotting antics than socializing with his crewmates.
Shop Keeper: He runs an entire antic shop that is often visited by Captain Heinrich Lehmann-Willenbrock and Lt. Werner whenever they need some equipment.
Captain Philip Thomsen
The navy's grand master of antics, and one of the grand masters of the antic order.
The Alcoholic: Thomsen has litearally one scene where he isn't drunk... and it's one of two appearances in the entire film.
Rousing Speech: The most commonly-used scene with Thomsen involves him delivering a drunken speech. Often he's used to make an announcement but he's also done straight speeches and bad stand-up comedy.
The Quiet One: Merriman rarely speaks in the parodies. This is mostly due to the fact that no foreign-language dubs of the film are known to be in circulation, although some of the videos use Shailene Woodley's dialogue from the German-language dub of The Descendants.
The Prankster: Lissie has actually been portrayed as one alongside Elizabeth Cole in the original books (Very Funny, Elizabeth to be specific), but it isn't as extreme or as ludicrous as with her depiction in the parodies.
Rousing Speech: Most of the parodies involving Samantha typically use the "Progress in America" speech scene in the film, which originally had Parkington denounce the horrors of child labour, altering the subtitles to make it look as if she was giving a speech about Xbox Live or SOPA.
Butt Monkey - Taken to the extreme when Kit shoots her best friend for trying to inform her of useless things.
Girly Girl - in contrast to Kit's tomboyish personality.
Butt Monkey: There are literally hundreds of parodies that centre around or involve Hitler trying to kill Justin Bieber, with varying degrees of success (this is a rare time when some untergangers are willing to let Hitler win). Outside of the parodies, he's widely hated by nearly everyone, to the point where there have literally been wars declared against him.
Foil: Toward Kate Bush. As the universe's representation of bad music.
The mirrored equivalent of Adolf Hitler. Unlike his counterpart in the main Parody Universe, Reltih manages to Take Over the World and is the overlord of his world. He wants to destroy Hitler, the other Hitlers, and pretty much the whole Parody Universe.