It's hard to definitively say what the absolute thinnest object in the world is because it depends on how you define "thinness" and what level of precision we're talking about.

Here are some contenders:

* Graphene: A single layer of carbon atoms arranged in a hexagonal lattice. It's only one atom thick, making it the thinnest material known, but it's still technically a sheet, not an object.

* Single-molecule chains: Scientists have synthesized chains of molecules just a few atoms thick and many atoms long. These could be considered objects.

* 2D materials: Beyond graphene, other 2D materials like molybdenum disulfide and hexagonal boron nitride are also incredibly thin, measuring just a few atomic layers thick.

* Atomically thin films: Scientists can deposit incredibly thin films of various materials, sometimes just a few atoms thick, for use in various applications.

* Individual atoms: At the most fundamental level, individual atoms themselves are incredibly thin, being only about 0.1 nanometers in diameter.

The answer to your question truly depends on how you define "object" and "thinness" in this context.

Let me know if you'd like to explore any of these contenders in more detail!