| nocardia brasiliensis | 26 | species | bacteria | bacteria | 37326 |
| nocardia asteroides | 51 | species | bacteria | bacteria | 1824 |
| nipah virus | 51 | species | viruses | viruses | 121791 |
| nigrospora sphaerica | 9 | species | plants | fungi | 114231 |
| newcastle disease virus | 93 | species | viruses | viruses | 11176 |
| new york virus | 7 | species | viruses | viruses | 44755 |
| neurospora sitophila | 11 | species | plants | fungi | 40126 |
| neotestudina rosatii | 2 | species | plants | fungi | 160030 |
| neoscytalidium hyalinum | 16 | species | plants | fungi | 1451147 |
| neorickettsia sennetsu | 18 | species | bacteria | bacteria | 951 |
| neofusicoccum mangiferae | 16 | species | plants | fungi | 463686 |
| neodiplostomum | 9 | genus | invertebrates | | 84101 |
| neodeightonia subglobosa | 1 | species | plants | fungi | 371117 |
| neobalantidium coli | 17 | species | invertebrates | protozoa | 71585 |
| nematodirus abnormalis | 2 | species | | helminths | |
| neisseria weaveri | 6 | species | bacteria | bacteria | 28091 |
| neisseria subflava | 14 | species | bacteria | bacteria | 28449 |
| neisseria sicca | 14 | species | bacteria | bacteria | 490 |
| neisseria perflava | 15 | species | bacteria | bacteria | 33053 |
| neisseria mucosa | 14 | species | bacteria | bacteria | 488 |
| neisseria meningitidis | 130 | species | bacteria | bacteria | 487 |
| neisseria lactamica | 31 | species | bacteria | bacteria | 486 |
| neisseria gonorrhoeae | 136 | species | bacteria | bacteria | 485 |
| neisseria flavescens | 11 | species | bacteria | bacteria | 484 |
| neisseria flava | 7 | species | bacteria | bacteria | 34026 |
| neisseria elongata | 9 | species | bacteria | bacteria | 495 |
| neisseria cinerea | 17 | species | bacteria | bacteria | 483 |
| necator americanus | 46 | species | invertebrates | helminths | 51031 |
| nanophyetus salmincola | 10 | species | invertebrates | helminths | 240278 |
| naegleria fowleri | 33 | species | invertebrates | protozoa | 5763 |
| myroides odoratus | 15 | species | bacteria | bacteria | 256 |
| myriodontium keratinophilum | 3 | species | plants | fungi | 150376 |
| mycoplasma salivarium | 17 | species | bacteria | bacteria | 2124 |
| mycoplasma pneumoniae | 93 | species | bacteria | bacteria | 2104 |
| mycoplasma hominis | 54 | species | bacteria | bacteria | 2098 |
| mycoplasma genitalium | 78 | species | bacteria | bacteria | 2097 |
| mycoplasma fermentans | 37 | species | bacteria | bacteria | 2115 |
| mycoleptodiscus indicus | 2 | species | plants | fungi | 745397 |
| mycocentrospora acerina | 11 | species | plants | fungi | 227734 |
| mycobacterium xenopi | 34 | species | bacteria | bacteria | 1789 |
| mycobacterium ulcerans | 46 | species | bacteria | bacteria | 1809 |
| mycobacterium tuberculosis | 238 | species | bacteria | bacteria | 1773 |
| mycobacterium szulgai | 18 | species | bacteria | bacteria | 1787 |
| mycobacterium smegmatis | 80 | species | bacteria | bacteria | 1772 |
| mycobacterium simiae | 25 | species | bacteria | bacteria | 1784 |
| mycobacterium shimoidei | 3 | species | bacteria | bacteria | 29313 |
| mycobacterium senegalense | 12 | species | bacteria | bacteria | 1796 |
| mycobacterium scrofulaceum | 31 | species | bacteria | bacteria | 1783 |
| mycobacterium porcinum | 7 | species | bacteria | bacteria | 39693 |
| mycobacterium peregrinum | 16 | species | bacteria | bacteria | 43304 |
| mycobacterium mucogenicum | 11 | species | bacteria | bacteria | 56689 |
| mycobacterium marinum | 51 | species | bacteria | bacteria | 1781 |
| mycobacterium malmoense | 22 | species | bacteria | bacteria | 1780 |
| mycobacterium leprae | 95 | species | bacteria | bacteria | 1769 |
| mycobacterium kansasii | 49 | species | bacteria | bacteria | 1768 |
| mycobacterium haemophilum | 26 | species | bacteria | bacteria | 29311 |
| mycobacterium gordonae | 31 | species | bacteria | bacteria | 1778 |
| mycobacterium genavense | 21 | species | bacteria | bacteria | 36812 |
| mycobacterium fortuitum | 60 | species | bacteria | bacteria | 1766 |
| mycobacterium conspicuum | 2 | species | bacteria | bacteria | 44010 |
| mycobacterium chelonae | 58 | species | bacteria | bacteria | 1774 |
| mycobacterium celatum | 16 | species | bacteria | bacteria | 28045 |
| mycobacterium bovis | 132 | species | bacteria | bacteria | 1765 |
| mycobacterium avium | 125 | species | bacteria | bacteria | 1764 |
| mycobacterium asiaticum | 7 | species | bacteria | bacteria | 1790 |
| mycobacterium africanum | 28 | species | bacteria | bacteria | 33894 |
| mycobacterium abscessus | 38 | species | bacteria | bacteria | 36809 |
| myceliophthora thermophila | 26 | species | plants | fungi | 573728 |
| murray valley encephalitis virus | 28 | species | viruses | viruses | 11079 |
| mumps virus | 61 | species | viruses | viruses | 11161 |
| multiceps serialis | 4 | species | | helminths | |
| multiceps longihamatus | 1 | species | | helminths | |
| multiceps glomeratus | -3 | species | | helminths | |
| multiceps brauni | -3 | species | | helminths | |
| mucor ramosissimus | 5 | species | plants | fungi | 90264 |
| mucor racemosus | 26 | species | plants | fungi | 4841 |
| mucor indicus | 8 | species | plants | fungi | 64623 |
| mucor hiemalis | 29 | species | plants | fungi | 64493 |
| mucor circinelloides | 27 | species | plants | fungi | 36080 |
| mucambo virus | 7 | species | viruses | viruses | 60875 |
| morganella morganii | 46 | species | bacteria | bacteria | 582 |
| moraxella ovis | 11 | species | bacteria | bacteria | 29433 |
| moraxella osloensis | 16 | species | bacteria | bacteria | 34062 |
| moraxella nonliquefaciens | 16 | species | bacteria | bacteria | 478 |
| moraxella liquefaciens | 2 | species | | bacteria | |
| moraxella lincolnii | 1 | species | bacteria | bacteria | 90241 |
| moraxella lacunata | 14 | species | bacteria | bacteria | 477 |
| moraxella cuniculi | 4 | species | bacteria | bacteria | 34061 |
| moraxella caviae | 6 | species | bacteria | bacteria | 34060 |
| moraxella catarrhalis | 87 | species | bacteria | bacteria | 480 |
| moraxella bovis | 35 | species | bacteria | bacteria | 476 |
| moraxella atlantae | 5 | species | bacteria | bacteria | 34059 |
| monongahela virus | 3 | no rank | | viruses | 2259728 |
| monkeypox virus | 35 | species | viruses | viruses | 10244 |
| moniliformis moniliformis | 14 | species | invertebrates | helminths | 10237 |
| moniliella suaveolens | 3 | species | plants | fungi | 64615 |
| moniezia expansa | 31 | species | invertebrates | helminths | 28841 |
| molluscum contagiosum virus | 36 | species | viruses | viruses | 10279 |
| mokola virus | 26 | species | viruses | viruses | 12538 |
| mogibacterium timidum | 11 | species | bacteria | bacteria | 35519 |