Forbidden Planet ending explained

What happens

Morbius realises the invisible killer is his own subconscious, given form by the Krell machine. He confronts it, orders the machinery destroyed, and dies. Adams sets the reactor to blow, and the crew and Altaira leave.

The last image

The crew's ship watches the planet explode far below, ending Morbius's world and the Krell's silent machinery with it.

What it says

The monster was never an invader. It was a mind's hidden self, magnified by technology. Morbius saves everyone only by admitting it is his. Destroying the machinery shows that power without moral maturity must be given up, not controlled.