The answer to that is skin.
That would be human beings.
The order of largest to smallest structures in the human body is organism, organ system, organ, tissue, cell, organelle, molecule, and atom.
The order of living things from smallest to largest in the body is: cell, tissue, organ, organ system, and organism.
The world's largest single-celled organism is the green algae Caulerpa.
The organism with the largest genome size is the marbled lungfish, also known as Protopterus aethiopicus.
The largest organism.
The organization of the human body usually is expressed from the smallest unit to the largest. Cells that are all the same form tissues, different tissues form organs, different organs form organ systems and different organ systems form an organism.
The organism with the largest genome among all living beings is the marbled lungfish.
The largest human organ is the skin.
Multi-Organism: The Great Barrier Reef in Australia, which is also arguably the largest organism on Earth. Single organism: The Great Blue Whale (Balaenoptera musculus)
The largest human organ is not actually "in" a human it is "on" a human. It is your skin, called the epidermis. "Inside" your body the liver is the largest organ.
A Kingdom is the largest group a organism can be classified in.