Jaw Breaker

Monster trying to get its teeth into you? Here's an unusual solution; force the creature's jaws apart until they break.

Oddly, this is almost always portrayed as causing instantaneous death (in which case it's usually taken to be a "cooler" version of a Neck Snap), when it should leave them alive but in crotch-stompingly horrible pain.

For some reason, Reptilian monsters are especially prone to this.

A nastier variant is to simply tear the jaw off altogether.

Examples

Comic Books

In Fifty Two, after Sobek's true colors are revealed, Black Adam finishes him off this way.
Pictured above: in an issue of The Walking Dead, upon being tackled by a zombie, Martinez sticks his hand in its mouth and breaks its jaw before it can bite his fingers. Okay he had gloves on, but still.
In Secret Six, Jeanette breaks King Shark's jaw this way. Somewhat subverted, as this doesn't kill him, but it obviously leaves him in excruciating pain.
Thragg does this to Dinosaurus in an issue of Invincible, but he lives.

Film

King Kong's signature move. He does it to dinosaurs and giant snakes in the 30s version, the 70s version, the 00s version and the video game based on it.
Mecha-Godzilla does this to Anguirus in Godzilla Vs. Mechagodzilla. He lives, though.
Derek kills a man in a disturbing scene in American History X with a curb stomp.
One of the deaths in Mirrors.
Yoko in The Grudge suffers this, as does Kanna in Ju On. The third The Grudge film shows that Gretchen also suffers this fate.
The "reverse beartrap" in Saw.

Literature

In His Dark Materials, Iorek tears his rival's jaw off. Symbolic, because the other was a liar.
Samson does this to a lion in The Bible.

Video Games

This is one possible execution animation for Ork Nobz in Warhammer 40000 Space Marine; pin their foot with your Power Axe and then break that jaw for the Emperor.
- And Titus does it with so much force that it makes the Nob'z head explode.
In God of War, Kratos finishes Cerberus this way, in order to steal the artifact held within its mouth.

Webcomics

The Adventures of Dr. McNinja: Doc does it to a zombie. Since it was undead, it doesn't really kill the thing, but it does prevent it from biting him.
- He doesn't stop with just removing the jaw, though. He proceeds to punch through it's spinal column, which is the part that kills it.
Part 4 of The Sacrifice has one of Bill's surgeons turn just as he's getting anesthetics. The ensuing struggle between her and the doctor has him tear her jaw off before she kills him and moves on to Bill.