If you thought Usain Bolt was the fastest runner ever, you thought wrong.
There's a far speedier mover out there - and no one as ever heard of her. She's never been near an Olympic stadium, and she's never won a gold medal in her life.
But as you'll see from the video above, "Sarah" is the proud holder of a the world record as the fastest living thing on the planet.
Ok, so the fact that she's a cheetah kind of gives her an advantage over Bolt. But last week she sprinted 100m in 5.95 seconds at Cincinatti Zoo, which recorded a running time of 61mph.
According to National Geographic, this is the fastest 100-metre sprint ever recorded of any living thing on earth.