What Harry Potter spell kills you?

The most obvious one is Avada Kedavra the killing curse, which speaks for itself, but there are various other spells that could be deadly or could be used to create something deadly. Sectumsempra for example, is simular to pulling a sWord on someone, it slices them open very easily, and then there are many other spells such as imperio, which could be used to control someone and make them kill themselves. It is simply a manner of imagination to use any number of spells in a deadly way.