Kate Middleton's knee is SCARING THE LIFE OUT OF ALL OF US.

We humans have long pondered whether spirits walk among us; whether lost souls in limbo are haunting our creaky hallways, lurking in dusty attics or pinching socks from the dryer.

Now, finally, we have proof.

Irrefutable photographic evidence uncovered by a Reddit user shows an actual, real-life ghost taking corporeal form in the Duchess of Cambridge’s knee.

Begone, demon! Image: Getty.

The image shows the 35-year-old casually strolling around outside London's Victoria and Albert Museum on Thursday, seemingly unaware or unperturbed that her meniscus is playing host to an otherworldly being.

A being that bares a striking resemblance to Casper, The Friendly Ghost. Or a jelly baby.

The palace is yet to comment.

Source: Screenshot/Amblin Entertainment.

Meanwhile, spurned on by coverage of this supernatural event, internet sleuths have unearthed disturbing evidence suggesting similar phenomena occurring in the joints of other public figures.

Including young US singers Selena Gomez...

Image: Getty.

And Miley Cyrus.

Ghost of an angry toddler. Image: Getty.

Two pressing questions remain:

Who are they?

And what do they want with our celebrities?

Speaking of ghosts... Patrick please leave Nina alone.

Have you ever had a ghost living in your kneecap? Tell us about it in the comments below.