Hollywood Satanism

Hollywood Satanism actually goes back to Medieval Europe, when it was believed that witches made a Deal with the Devil to gain their power and engaged in rituals intended to mock Christianity just for the heck of it. Basically, it was thought that Satanism (which didn't actually exist at that point) was essentially reverse Christianity, and the idea stuck. Rosemary's Baby gave it a shot in the arm in the 60's, and during the 70's-90's the Satanic Panic ensured that many of the tropes associated with it became ingrained in the public consciousness.

You know you're looking at Hollywood Satanism when you see Satanism portrayed as a Religion of Evil with bizarre, often disgusting rituals and a particular fondness for Human Sacrifice. Common hobbies of the Hollywood Satanist include sacrificing your cat, slipping backmasked messages into popular music to corrupt the youth, and engaging in carefully-calculated world-domination schemes that have been in the works since the beginning of time (which usually involve breeding the Anti-Christ - extra points if he's Aryan!).

Individual Satanists are often presented as criminals, and of course a single ritual performed by drunk teens will always make the Big Guy himself (or one of his minions) show up to raise hell.

Real Life Satanism can be divided into two categories. One of them, sometimes called "LaVeyan Satanism" after one of its more famous figures, doesn't believe in Satan as a physical entity, and instead refers to him as a symbol for freedom to follow your own desires and/or for fighting against tyranny. The other one worships or reveres Satan as a deity. Both of them, generally speaking, view Christian morality as self-destructive for both individuals and society. It's a religion whose followers, generally speaking, are no more or less likely to be "evil" than the followers of any other religion, though their sense of what constitutes right and wrong is likely to differ from the mainstream. And no, human sacrifice is not a part of it (symbolic sacrifices may be -- but that is Not So Different from the Christian Communion, which is itself a symbolic sacrifice of the body and blood of Jesus).

Compare Religion of Evil, Always Chaotic Evil. Also compare Your Terrorists Are Our Freedom Fighters.

Fanfic

 * My Immortal is probably the most confusing case of Hollywood Stanism... er, Satanism that ever existed. The characters worship Satan (Satan, not Voldemort, whose nickname in high school was Satan), but we never really see them do anything beyond getting high and yelling at people. One implication is that they worship Satan by insulting preps and getting high on "crak".

Film

 * In Spawn, a pair of "weekend Satanists" bump into Spawn and Violator and completely freak out, much to Violator's disgust.
 * Rosemarys Baby.
 * Race with the Devil: Two ordinary couples on an RV trip witness a Satanic human sacrifice and are pursued by the cultists, who wish to silence them.
 * The Omen series.
 * The main villains in Drive Angry are this. Oddly enough, though,
 * The Seventh Victim
 * The entire plot of the B-movie Devils Prey.
 * An indie band of Hollywood Satanists form a major plot point in Jennifer's Body.
 * Demonic Toys does this to an extent. A demon in the form of a child (a la Rosemary's Baby) dies shortly after being born and is buried near a toy factory. Blood is spilled and he comes back to life. He has a baby doll draw a pentacle on a floor in the warehouse, complete with candles, since he plans on having sex with a pregnant cop in the circle so he can possess the fetus. Oh yeah, and this is on Halloween.
 * Satanists who lure a babysitter for a ritual appear in The House of the Devil.

Literature

 * In Good Omens, Crowley identifies two kinds of Satanist: ordinary people who are Satanists because their parents were and don't usually think about religion except when they go to Black Mass, and the other kind who give demons (or Crowley, at least) the creeps.
 * Russ Martin's series about an evil Satanic organization, including The Possession of Jessica Young, The Obsession of Sally Wing and The Education of Jennifer Parrish.
 * In Conspiracies, one of the conventioneers had been brainwashed into accusing her father of molestation and Satanism, by a shrink her mother hired to ensure she's keep custody in the divorce settlement. Years later, she's plagued by nightmares of terrible encounters with Hollywood Satanism that never happened.
 * Any Chick Tract trying to portray Satanism.
 * Ape and Essence by Aldous Huxley has literal Hollywood Satanism, with the worship of Belial in After the End Southern California presented in the framing story as the unproduceable opus of a Hollywood screenwriter.
 * Rosemary's Baby, in which not-so-friendly neighborhood Satanists see to the impregnation of the titular Rosemary with the spawn of Satan and the Anti Christ.
 * Babylon Rising features a shadowy and secretive group of Satanists that have existed since Satan made contact with a Babylonian priest during the reign of King Nebuchadnezzar and started up a cult.

Live Action TV

 * One time on The X-Files, the agents encountered a group of "real" Satanists, who were accused of being the Hollywood Satanist type. That they were all school teachers didn't help. It ends up being a parodic subversion, in that the Satanists are far from the Hollywood Satanism stereotype; they never do human sacrifices or molest children or anything like what the moral panic suggests, they're just normal, everyday people just happen to worship Satan. Unfortunately, one of their now-teenage kids has gotten some hazy childhood memories confused with the sensationalist stuff she's seen in the media, thus prompting an hysterical panic; and that's before things go epically off-the-rails when one of their kids accidentally does summon Satan and the Prince of Darkness goes, "'Manifestation of personal desires,' my ass" and starts killing people.
 * Starsky and Hutch episode "Satan's Witches": While on vacation, the title characters run into a town being threatened by a cult of devil-worshipping Satanists.

Music

 * The song "The Number of the Beast" by Iron Maiden tells of a man witnessing Satanic rituals that horrify him.
 * Murdoc Niccals of the Gorillaz is openly satanist, is never seen without the inverted cross on his neck and has apparently made a Deal with the Devil.
 * Marilyn Manson claims to be a Satanist and plays to this stereotype on occasion.
 * Alice Cooper is an interesting subversion: he's often been accused of being the Hollywood Satanist, and his stage shows may very well give the impression to some that he is... when he's actually a Christian.

Webcomics

 * Parodied in the "KITTEN II" storyline of Sluggy Freelance. Two of the minor characters in the Slasher Movie parody turn out to be Satan-worshippers who betray the group. Behold the proud majesty and sheer classiness of their '80s Headbanger Satanic Rituals!

Western Animation

 * Parodied in Metalocalypse, when Murderface joins the Church of Satan and goes to Black Mass. They come across as rather timid, cowardly people that can't stand up for themselves. Then played straight in The Stinger, when the Church of Satan actually does summon a demon.
 * Subverted on Moral Orel. Coach Stopframe worships Satan believing him to be some powerful being that can help him win over Clay's heart and help the schools team. When he joins actual satanists, they turn out to a bunch of sloppy hedonists.

Other

 * The Conspiracy Theories associated with the Satanic Panic, full stop.