When 'kill off' refers to an actual death or ending, it's typically in a serious or negative context.

Literal Endings

Commonly used to discuss environmental impacts where human actions cause harm to ecosystems.

Environmental Usage

Can imply unintentional consequences when actions inadvertently cause destruction or an end.

Often used to discuss market competition where new developments may cause smaller entities to fail.

It can also be used metaphorically to express the destruction of abstract things like hopes or plans.

In narratives, 'kill off' can create dramatic plot twists and significantly change the story's direction.

Using 'kill off' for a character can lead to strong reactions from the audience, positively or negatively.