Single-celled eukaryotes are included in:
Protista is the Kingdom that includes only unicellular eukaryotes. Many algae, diatoms, and protozoans such as Amoeba, Paramecium, and Euglena are a few members of Kingdom Protista. Kingdom Monera consists of prokaryotes.
Fungi are eukaryotic organisms. They consist of both unicellular (e.g. Yeast, Molds) and multicellular (e.g. mushrooms) organisms.
Archaea comprise a group of prokaryotic single-celled microorganisms, and are the most ancient forms of life. Unlike bacteria, their cell walls do not contain peptidoglycan.
Monerans don’t have well-defined cell structures like the nucleus or organelles. This kingdom includes bacteria, cyanobacteria (blue-green algae) and mycoplasma.