A Royal Marines Commando.

The name comes from the old style Royal Marines uniform, which had a leather neck collar.

Literally everyone, ever. Including the writer of this definition.

Royal Marine (British Special Forces). Known to each other as "Royal" but the rest of the British Forces know them as bootnecks. This nickname is derived from them cutting the top from a leather boot and wearing it like a modern neckbrace to stop sailors cutting their throat while they guarded officers on board British sailing ships in the days of old.

A bootneck is a Royal Marine Commando.