!!The comics:
* CompleteMonster: In the [[CosmicHorrorStory dark world]] of ''ComicBook/{{Hellboy}}'', Nimue, the [[GodSaveUsFromTheQueen Queen of Blood]], reigns supreme as the greatest monster. Once a mighty sorceress who betrayed the great Wizard Merlin and imprisoned him [[AndIMustScream to live eternally in his own grave]], Nimue was imprisoned for 1,500 years by the witches of Britain. Upon her revival to lead the Wild Hunt, Nimue destroys the other witches of Britain and sets about marshaling an army of the Fae. When one ambassador comes to her to say his king will stand with her, Nimue forces him to murder his king, come out his heart and forge her a new crown with it. Nimue launches vicious purges to ensure there is no threat to her rule, intending to exterminate humanity to the last man. When defeated and being dragged to hell by the witches she'd murdered, Nimue spitefully [[TakingYouWithMe tears out Hellboy's heart to ensure she won't face damnation alone]].
* EnsembleDarkhorse: Karl Ruprecht Kroenen, Kate Corrigan.
* HolyShitQuotient: The vision of the apocalypse in ''King of Fear'', not to mention [[spoiler:Hellboy paying back the Baba Yaga... with his *own* eye]].
* SomeAnvilsNeedToBeDropped: You ultimately ''do'' have a choice on what to do with your life, no matter how many times you're told otherwise.
* WhatDoYouMeanItWasntMadeOnDrugs: Read the "Our Angels Are Different" entry.

!!The films:
* DracoInLeatherPants: Prince Nuada, [[WhiteHairBlackHeart naturally enough]] for an expy of [[ElricOfMelnibone Elric]].
* EngagingChevrons: Parodied in the first movie, a guy with a high-tech flamethrower backpack goes through a long, drawn-out start-up sequence, only to be eaten by the thing he's trying to kill before he can use it.
* EnsembleDarkhorse: Kroenen, for being an AdaptationalBadass and CreepyAwesome clockwork zombie.
* EvenBetterSequel: Despite diverging even more from the source material, ''The Golden Army'' is liked just as much as, if not more so, than the first film.
** Although it's notable that Mignola eventually eschewed the pulpier villains and Nazis of the earlier stories for a similar path through folklore and mythology, while the BPRD series handled threats that had been notched up early in Hellboy's run.
* FridgeBrilliance: Nuada's fighting style is mostly based on speed and agility, doing all kinds of elaborate maneuvers to land hits on his opponent without being hit back. And he shares a magical link with his twin sister that means that everything that physically happens to him also happens to her and vice/versa. It stands to reason that he developed his fighting style in order to keep his sister from getting hurt along with him, supported by the first fight scene where he gets hit in the face and then turns to Nuala, clearly horrified as they both start bleeding.
** Hellboy's KindHeartedCatLover traits make sense due to his hellish origins. Cats are believed to be the gatekeepers of the underworld.
* FridgeLogic: The second movie in particular has {{Plot Hole}}s you could drive a garbage truck through. See [[{{Headscratchers/Hellboy}} the Headscratchers page]] for a complete list.
* HoYay: It says something about the writers (or maybe the actors) that one of the most romantic scene in the either of the films is two dudes getting drunk and singing "Can't Smile Without You" to each other.
* JerkassWoobie: Nuada.
* MagnificentBastard: Nuada again. He's a [[WellIntentionedExtremist genocidal dick]], but you can see where he's coming from.
* MoralEventHorizon: Prince Nuada starts off by unleashing a swarm of ravenous tooth fairies in a room full of people, the tooth fairies ate every last bit of everyone in that room till there was nothing left of them. There is absolutely no purpose to this either, as he already has what he came for. He does it just because they're humans.
* PeripheryDemographic: The first film received a good review from [[http://www.pluggedin.com/videos/2004/Q1/Hellboy.aspx Focus on the Family]], of all people.
* TearJerker: [[spoiler:Nuala's]] sacrifice, particularly because it makes Abe of all people shed a tear.
** The death of [[spoiler:Professor Broom in the first film.]]
* UglyCute: "[[http://www.youtube.com/watch?v=CxVPrrNZntI I'm not a baby]], [[CrowningMomentOfFunny I'm a tumour]]."
** Nuada, if you're tired of yet another WellIntentionedExtremist ranting against the black and white evil that is humanity.
* VisualEffectsOfAwesome: And relatively small budgets.

!!The animated films:
* WhatDoYouMeanItsNotForKids: The animated films are in no way child-friendly, and in some ways are DarkerAndEdgier than even the live-action films.

!!The video games:
* TheProblemWithLicensedGames: Both Hellboy games had outdated graphics and repetitive gameplay, and the first one was full of bugs. Although ''The Science of Evil'' was supervised by Mignola and Del Toro, it didn't make up for the programming shortcomings.