A car runs over a man's head as he lies in the road. Only the characters in the car's reactions are shown (they don't see what happened and assume it's a speed bump), but the noise is quite graphic.

Not exactly squashed but one character's head gets severely mutilated by an accident involving a utility pole and another character smashes his head on a desk repeatedly.

Oberyn Martell's head is crushed by the Mountain.

There is NO literal head squishing in the movie. Thor's head is seized and threatened to be squished, but THAT IS ALL.

Probably the goriest part of the movie. You’ll know when it’s about to happen.

Pennywise manipulates their body throughout, including squishing their head flat. Twoards the end their head also deflates like a baloon.

There's a fair amount of decapitation which leads to heads being kicked and carried around

Yeah, a bunch of walkers get their heads squished throughout the show, there are so many instances of this happening that I can't think of just one example.

Does a head getting eaten count as squashed? I'd say yeah, but some my disagree.

Twice throughout the movie a head is squashed, one being possibly the most gory death in the franchise.

A head is run over by a lawn mower and is shown again stitched back together

Heads explode in the game from direct gunfire and other assaults.

Roanoke

One character had his head bashed in by a metal ball, although I don't think there was any gore shown, only blood.

There's a very graphic scene where a man squashes his wife's head in with his bare hands.

In the first episode of Golden Wind Giorno uses one of his abilities to send the damage from an attack back to his attacker, Leaky Eye Luca. This causes the back of his head to cave in with an imprint of the shovel he was attacking Giorno with.

Deputy gets his head squished by gator while being chomped on

One gets ripped off, so yea

Not so much squashed. More beaten against a wall.

If you follow the Dark Brotherhood questline, there is a head-squashing.

several characters are graphically shot in the head

Hand man go bye bye

Several heads /are/ blown off by a gun, though

This happens multiple times, to multiple characters, in multiple episodes, in gory detail.

a character gets bashed in the head with a hammer while gardening

Someone's head is crushed with an ATM machine.