''Bloody Birthday'' is a 1981 [[SlasherMovie slasher]] horror film about three sociopathic children born under an eclipse as foretold that anyone born under an eclipse of Saturn would have a personality flaw, the children are Debbie, Curtis, and Steven, Joyce Russel and her brother Timmy must work together to stop their murderous rampage.
!!Tropes featured in this film include:
* AdultsAreUseless: Apparently, everybody above the age of twelve carries the IdiotBall at all times.
* AxCrazy: All three children, Curtis in particular.
* BatterUp: Steven beats Debbie's father Sheriff Brodie to death with a baseball bat
* CassandraTruth: Nobody believes Joyce and Timmy that Debbie, Curtis, and Steven are killers.
* ChivalrousPervert: Curtis is quite perverted for someone who's only ten years old.
* CreepyChild: The three main children when they're not trying to be cute.
* [[MonsterClown Creepy Clown]]: The birthday clown wearing a "I Just Can't So No" T-shirt.
* DeathBySex: Curtis teaches this to one unfortunate couple getting it on in the back of a van.
* DisproportionateRetribution: They murder their teacher Ms. Davis because she won't allow them a day off from homework for their birthday parties.
* EnfantTerrible: The three children were sociopaths from birth.
* EyeScream: Beverly gets an arrow through the eye by her psychotic younger sister Debbie.
* FinalGirl: Joyce, the wholesome teenager who along with her young brother is the last to confront the killers.
* KarmaHoudini: [[spoiler:Curtis and Steven are arrested while Debbie escapes with her mother under a new identity so she can continue to murder]].
* LackOfEmpathy: The three murderous kids were born during an eclipse of Saturn, which removed all of their emotions.
* MsFanservice: MTV's Julie Brown. (No, not Downtown Julie, the other one.)
* NerdGlasses: Curtis who is one of the most intelligent children in the film wears a pair of these.
* TamperingWithFoodAndDrink: Curtis may or may not have poisoned cake frosting, but Joyce catches him with poison in hand and makes a scene at the birthday party to stop anyone from consuming possible bad cake.
* TooDumbToLive: Even though she knew about the peephole Debbie set up Beverly never thinks to cover it up, which results in her death.
* WoundedGazelleGambit: Curtis abuses this when Joyce tries to uncover their crimes.