White blood cells (WBCs) are categorized into five distinct types: neutrophils, monocytes, lymphocytes, eosinophils and basophils. Each type plays its own role in fighting viral, fungal, bacterial and parasitic infections.onocytes. Monocytes are the biggest in size among the five types of white blood cells. Their numbers in blood fall between 200 and 800 per cubic mm of blood, accounting for about 5 to 8 percent of the total WBC count.