Nightmare Fuel / Batman: Under the Red Hood

  • The fact that Jason managed to get an Oh Crap! reaction out of The Joker. The. JOKER.
  • Joker's absolutely brutal beatdown of Jason Todd in the opening scene.
  • Red Hood's commandeering of several gangs and drug dealing operations by arranging a meeting. One of the more skeptical dealers asks why they should work for the Hood. Cue duffel bag.
  • The Joker's almost casually brutal slaughter of four of Black Mask's gunmen, starting with just these words: "May I have some water?"
  • Jason Todd's resurrection scene and his sequential freak-out. After they drop him into the Lazurus Pit, he bursts out of the water screaming like a madman, with a crazed look in his eyes. He kicks the crap out of Ra's Al Ghul's men, taking out one by jamming his thumbs right into the poor sucker's eye sockets. He then escapes by jumping out the window. His actions from this entire scene are borderline... animalistic. Though resurrection via a Lazarus Pit renders the one resurrected momentarily insane, even Ra's Al Ghul was afraid. What makes it more terrifying is Vincent Martella's performance. Just imagine Phineas Flynn screaming like he's in horrible agony.
  • Black Mask's face, though not his character.
  • Red Hood shooting a Molotov cocktail that a mook was holding, setting him on fire (a sight that the audience is mercifully spared).
  • The Joker hijacking Jason's Taking You with Me gambit just so he'll get to die with Batman, proving that the Clown Prince of Crime is indeed a legitimate self-destructive lunatic.
  • Nightwing and Batman's take-down of Amazo, which involves burying bladed batarangs in his ears and affixing C-4 to his eyes before detonating it. Imagine them doing that to an actual human being...
  • One of the kills the Red Hood does: he stabs a criminal in the eye with a tazer and then turns it on full-force, short-circuiting his cybernetic eyes and blowing up his brain. While in the movie, it's done to one of the Canon Foreigner group, the Fearsome Hand of Four; in the comic, it's done to Captain Marvel baddie Captain Nazi.
http://tvtropes.org/pmwiki/pmwiki.php/NightmareFuel/BatmanUnderTheRedHood