Hiss Before Fleeing

The heroes have fought the monster, given it some good licks, but the monster isn't done yet. It pauses for a moment to hiss or screech loudly with its fangs out, its arms outstretched and claws extended, before leaping offscreen. Perhaps it just wanted to get the last word in. Time for the heroes to pursue.

Maybe it wants to frighten the heroes away, or just wants to vent some rage at being beaten up by mere humans. Whatever the case, it's Villain Exit Stage Left! Mostly, it's animal monsters that do this, though vampires and aliens are also fond of hissing before fleeing. Occasionally, anything that cause a burning reaction or Glamour Failure is sure to make the creature hiss before fleeing.

The exit counterpart to Roar Before Beating. It seems like while monsters roar to say hello, they hiss to say goodbye. This is a very common trope, possibly an Undead Horse Trope. It appears to be based on the idea that all animals are cats.

Examples of Hiss Before Fleeing include:

Anime and Manga

Hellsing. Episode 7, Duel has the scene where Vatican priests tell Integra that their paladin is about to ambush their soldiers in the subway, right when Integra and Alucard were about to kill said priests in a museum. Integra doesn't actually hiss, but she does make a similar noise, give one hell of a mean glare, and promptly spins around and walks away (retreating) defiantly, followed by Alucard who does something very similar. Subversion seeing as they're the good guys.

Comics

A rat creature in Bone does this after an unsuccessful face-down with the Red Dragon.

Film

Alien, possibly the Trope Codifier.
Parodied by Pee Wee Herman in Pee Wee's Big Adventure: Pee Wee hisses, everyone else flees.
Things in John Carpenter's The Thing scream a lot.
Very common with vampires. See Underworld for a good example or two.
Avatar: Appears to be an instinctive gesture of contempt used by the Na'vi - and often as not is Hiss Before Righteous Ass-Kicking instead.
Frank Butterman of Hot Fuzz at the end of the bar scene in the movie's climax, though that was more of a growl than a hiss.
- Not more like a growl, but that is a lion's growl.
Mad Max. Toecutter, the leader of the biker gang, does this after Max shoots dead The Dragon. He then jumps on his bike and roars off, but Max is soon after him.
- Wez does this in The Road Warrior, just after leaping out of the oil drillers' compound.
The Gremlins tend to hiss at their attackers before they flee a scene.
Grima Wormtongue does this in Ralph Bakshi's The Lord of the Rings, an action taken directly from the book.
- Shelob does something very like this trope after Sam cuts her a good one in The Return Of The King, although her "voice" is pretty much nothing but hissing in any case.

Literature

Happens at the end of several battles in the Warrior Cats series, naturally.
As above, Grima Wormtongue does this in The Lord of the Rings as he leaves Theoden's service.
The newly turned Lucy in Dracula as Helsing driving her back with a cross before escaping into her tomb
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Live Action TV

Vampires in Forever Knight always hiss when they expose their fangs. More than a few times, this has been immediatly before a withdrawal.
Though he's too old to flee, Gormogon's mentor on Bones hisses viciously at Brennen and Booth when they confront him at a nursing home, then "retreats" into sullen (feigned?) senility.
Angel and Buffy both did this in their earier episodes, though both waned shortly into their respective runs.
Doctor Who's "The Vampires of Venice". If you're lucky, the vampires flee after they hiss. If not, you will.

Video Games

Seen early on in with a Spider Splicer in BioShock (series).
Alma does it in the second First Encounter Assault Recon game, after you fight off her rape attempts.
Mileena in Mortal Kombat does this when she is tagged out in a two-on-two match.

Web Comics

Shortpacked! example: when Robin gets into a Cat Fight with Sarah Palin, the latter does this when confronted by reporters, because free press burns her. Moments later, Robin similarly flees when Amber reminds her that it's her turn to clean the toilet.

Web Original

For some reason, The Angry Video Game Nerd of all people does this to The Nostalgia Critic in the early stages of their Final Battle. Uh, that is, their second Final Battle.

Western Animation

Played for laughs in South Park in the episode where Butters thought he'd turned into a vampire. He does this because he thinks it sounds menacing. It was actually hilarious, which made it even funnier when people were genuinely shocked by it.
In The Simpsons "Bart Sells His Soul", Bart does this when he is caught trying to buy Ralph Wiggum's soul. For bonus points, he disappears into smoke like a supernatural being and his eyes are briefly reptillian-slitted.
- Another Simpsons example is Hugo in one of the Halloween specials.
- Still another example has bunch of comic convention nerds scrounging in a trash can, who look up with red eyes and hiss when a flashlight beam falls on them, causing them to run away.
Momo from Avatar: The Last Airbender when Aang and Sokka reach out to him. The former wants Momo as a pet and the latter wants him for lunch.

Real Life

Many species of animal (Including cats, snakes, and toads) will puff up their bodies and hiss loudly to look more intimidating before simply running away.