Choke Holds

There are two kinds of chokes. Blood and air.

The air choke is when someone is choked unconscious by cutting off his air supply. The air to the lungs is suspended. In fiction the person chokes and flails in silence, and after maybe thirty seconds he is rendered unconscious. In reality, cutting off someone's air supply would take several minutes and he'd be at full strength the whole time. Do not choke someone this way (Fridge Logic: If you're reasonably athletic and don't smoke, you can probably hold your breath for over a minute voluntarily. Try it; there's no risk. Why should a choke hold be any different?)

The blood choke is when someone is choked unconscious by cutting off his blood. The supply of blood to the brain is suspended. In fiction the person goes cross-eyed and immediately succumbs to unconsciousness. In reality, the process takes a few seconds and the victim understands what's happening and can protest, in the brief window available. Do choke someone this way, if you know what you're doing. If you don't, you can kill someone. Sometimes a blood choke causes the collapse of the arteries carrying blood to the brain and, inevitably, death. This is why cops no longer employ "The Sleeper Hold". It kills.

It's possible for a karate chop to be a form of a choke. If a blow to the neck is intended to hit the carotid artery and briefly interrupt blood flow it's a stunning blood choke. If it's a blow to the side of the neck it's intended to strike the vagus nerve and is a Pressure Point strike. The typical depiction of a karate chop is a Tap on the Head.

Instant Sedation is very common. Compare Tap on the Head where unconsciousness is rendered with a blow, The Paralyzer (Vulcan nerve pinch included). Also, the Vorpal Pillow, where a choke hold causes instant death.

This is a choking trope.

Examples of Choke Holds include:

Anime and Manga

In Street Fighter II V, Bison does this to Chun Li, in the midst of a psycho power-fueled rage, but nearly goes too far.
Shinji chokes Asuka in Neon Genesis Evangelion?!
In Genshiken, Hato applies one on Kuchiki to prevent Kuchiki... eeer... molesting Madarame. Unfortunately for Hato, the shamelessly perverted Kuchiki suddenly discovers he has a fetish for it.
In Berserk, during the love scene between Guts and Casca, Guts ends up having a flashback to his traumatic rape at the hands of Donovan, which nearly results in Casca getting strangled to death before he manages to snap out of it.

Film

Guy Ritchie's Sherlock Holmes features both chokes at the same time. A thug sneaking up on Holmes is put in a blood choke by Watson. To prevent the Mook from screaming, Holmes immediately pinches off his nose and mouth. They chat for a bit and, once the thug has passed out, move on. At the end of the film, a big mook has to be slowly air choked because he's just too darn big for anything else.
Darth Vader's Force Choke appears to be a long distance mystical air choke. Slow, unpleasant, unstoppable. Very dark-sidey.
Two chokes appear in Never Say Never Again. James uses a sleeper hold on a Mook guard during Unwinnable Training Simulation opening and an assassin uses a sleeper hold on one of the attendants at Shrublands.
In The Princess Bride, The Man in Black knocks out Fezzik with a blood choke. It takes several minutes and they have a rather cordial conversation all the while.
In Sneakers Dick Gordon knocks out Bishop with a sleeper hold. In contrast to the repeated Tap on the Head he's been given up to this point, it's an act of mercy.
Count Yorga: The titled character loves doing these when he can and its always fatal.
In The Dark Knight, Bruce Wayne does this to Harvey Dent.
In Do the Right Thing, Radio Raheem dies from a police chokehold, sparking off a riot.

Literature

In The Bishop's Heir, Dhugal (who doesn't then know he's Deryni, never mind controlling his shields) reacts badly to the psychic energies unleashed at Duncan's consecration as bishop. Morgan uses a choke hold on Dhugal to get him away from the cathedral via Transfer Portal and avoid unwanted attention from potentially hostile clerics when Dhugal's shields prove impossible for Morgan to breach.
A form of the "sleeper hold" variant comes up in Yoda: Dark Rendezvous. Weak but Skilled Padawan Scout has a particular move where she can grab someone's throat, cut off the blood flow, and render them unconscious in seconds without permanently damaging them. She uses it in Jedi Initiate tournaments to great effect. Scout is herself grabbed and held up by the neck later in the novel, and later still is on the receiving end of a Force Choke, and in the narration we see her struggle to breathe and think past the reduced blood flow.
In The Dresden Files Harry is grabbed by the skinwalker, and notes that there are two ways to choke someone into unconsciousness - the quick way, and the slow and painful way. Naturally, the skinwalker chooses the second one.
An executioner who kills the condemned by strangulation tries to do this to Conan the Barbarian, but his thick neck muscles prevent him. Conan then shows off his own strangulation skills.

Live Action TV

Burn Notice: Michael Westen is adept at the blood choke. His victims rarely cry out, but they rarely have time.
Law and Order features a victim of a fatal blood choke. A military man upset at a Jerk Pacifist mocking his dead son employs a sleeper hold blood choke. It leaves telltale bruises over the victim's carotid arteries.
Subverted by Angel. Someone tries to air choke the titular character only to learn, to his dismay, that that doesn't work on vampires.
- The demon tentacles one: "Yeah...vampire...strangling...not gonna happen." *Slashes tentacle with knife*
While Dexter prefers to sedate his targets, he's been known to strangle them into unconsciousness. Acceptable, considering what he plans to do with them doesn't really require them to be in the best health anyway. His brother was considerably more fond of the sleeper hold, although his goals were basically the same.
In an episode of NCIS, a sleeper hold accidentally kills someone.
Ray Langston does it to a suspect on CSI "Blood Moon", all the while going on about what's it's doing to the guy.
The patient of the week in one episode of House stymies the team until it turns out that he's a masochist whose sex-play includes being repeatedly choked by his Mistress. Among other things, this has caused damage to the arteries in his neck.

Professional Wrestling

This is a standard (if illegal) move.

Video Games

Deus Ex Human Revolution - one of the non-lethal takedowns.
Metal Gear Solid. Snake can sneak up on guards, grab them by the neck, and throttle them unconscious. When they wake up, they're perfectly fine. Handled slightly realistically in that Snake can kill a guard by throttling him until his neck breaks. In MGS3, if guards are hungry and weak, Snake can instantly knock them out with an Unnecessary Combat Roll.
- After beating Sniper Wolf for the first time, Snake himself got knocked out this way though.
This is how Batman performs a Silent Takedown in Batman: Arkham Asylum.
In some of the later Splinter Cell games, Sam uses a choke hold as a non leathal takedown of enemies he has grabbed. The older games had him hit them on the head with his pistol.

Webcomics

In El Goonish Shive, sensei Greg teaches a blood choke to Grace, in order to sedate Dex who is wreathed in flames, and summoned a bunch of puppet creatures to keep them busy. Humanoid creatures.

Western Animation

Jonny Quest TOS episodes, "The Quetong Missile Mystery", Race Bannon uses a sleeper hold on a Mook guard.
Of course, there's Homer Simpson and his infamous chokeholds on Bart, though there doesn't seem to be any ill effects on the part of Bart.

Real Life

Blood chokes are part and parcel of martial arts and MMA. If an MMA fighter taps out half a second after an arm goes 'round his neck, it's because he's about to pass out.
Air chokes are, as has been noted, not very good for knocking people out—but the pressure they exert on the trachea can be extremely uncomfortable, and the person escaping the choke might still be coughing an hour after being released.