There are some monkeys out there that are so small that they could fit into your hat. Beware, though, because these cute little demons can be little devils. Here are the smallest monkeys in the world.

Anyone who has been in the presence of a monkey will know that, no matter how cute and cuddly they might seem, they're no walk in the park.

These strange animals can come in many shapes and sizes, and the biggest are the scariest.

But the smallest? The smallest are more crafty than you'd think.

Cats Cat has hilarious reaction to his own reflection!

So what monkey holds the record for smallest in the world? Which monkey is so tiny that it puts other primates to shame? Oh, and what other small monkey breeds are there?

Let's do some monkeying around to find out.

Measured from head to torso, the pygmy marmoset is the smallest monkey in the world.

Native to the Amazon rainforests of South America, these adorable little animals are social beings that live in groups of two-to-nine. They have an IUCN status of "vulnerable," primarily due to habitat loss through deforestation.

Pygmy marmosets generally eat tree gum, which they pull through gnawed holes in the bark of particular tree species. They also like to chow down on a variety of insects. Interestingly, these tiny little monkeys generally settle down around a sap and gum hole, depleting it before moving on to a new home.

Pygmy marmosets generally measure between 4 and 6 inches in height, from head to feet. They are often so tiny that they could fit in the palm of your hand, and their children are so small that they could fit on your thumb.

You could hold them too, as they generally only weigh about the same as a chocolate bar - around 4 ounces.

One particularly interesting fact is that pygmy marmosets are not the smallest primate, only the smallest monkey. The award for the smallest primate goes to the mouse macaques, which average only 3–5 inches in height, when measured the same way. They also weigh considerably less.

The pygmy marmoset is not the only tiny monkey in the world, though it is the tiniest. There are a vast assortment of small little primates all over the world, from all over this great green globe of ours. Indeed, some even vaguely come close to beating the smallest monkey breed in the world!

Here are a few other small monkey breeds:

• Talapoin monkey (height of 10–16 inches)
• Squirrel monkey (height of 10–14 inches)
• Cotton-top tamarin (height of 8–10 inches)
• Common marmoset (height of 7–8 inches)
• Roosmalen's dwarf marmoset (height of 7–8 inches)

This is by no means a complete list. There are many tiny monkeys out there, all of which will steal your hat if you leave it behind. Don't make that mistake around these little buggers.

Considering that most monkeys look pretty horrifying, it is probably a safe bet to say that the pygmy marmoset is the cutest monkey, or even primate, in the entire world. Now, look, they aren't the cutest animal in the world, that's for sure, but they're pretty adorable.

Let's be real though, it's still not a good idea to leave your sandwich sitting unattended if there are monkeys around. You may enjoy the cuteness, but your stomach's not going to be happy!