What characteristics make viruses different than any of the organisms found in the 6 kingdom system?

Organisms are placed into these categories based on similarities or common characteristics. Some of the characteristics that are used to determine placement are cell type, nutrient acquisition, and reproduction. The two main cell types are prokaryotic and eukaryotic cells

Viruses are unique organisms. They do not belong to any kingdom due to the fact that they are not made up of living cells.