This blocky gal right here is the Funko Vinyl Cubed Harley Quinn.
The Vinyl Cubed figures are designed to be interchangeable. Their heads and feet are held on to their torsos via magnets.
It's a really cute concept and almost forces you to buy more than one, because once you open one up you want to start swapping parts between them.
I much prefer the more rounded, organic look of your standard Funko POP! figure over the squares of these little Vinyl Cubed figures, but the magnetic gimmick makes up for their blockiness. Now that I have Harley I am tempted to get another, possibly Batman, in order to do a head-swap and give Harley a bat costume.