A single-celled creature with no nucleus and other membrane-bound organelles is known as a prokaryote.
Prokaryotic cells, unlike eukaryotic cells, lack a membrane-bound nucleus. Instead, their genetic material is found in the nucleoid, a part of the cytoplasm.
Prokaryotes do have chromosomes.
Prokaryotic chromosomes have a circular form and are found in the nucleoid of prokaryotic cells.