Erythrocytes are Red Blood cells. (Note the RBC's are not actually cells.)
The prefix "eryth" means red. It is derived from the Greek word for red, "erythros."
Erythrocyte is not a type of leukocyte; it is a type of red blood cell responsible for carrying oxygen. Leukocytes include monocytes and basophils, which are different types of white blood cells involved in the immune response.