• Marolia Mulsant, 1856
• Marpolia C.D. Walcott, 1919 †
• Mirolia Ballmann, 2004 †
• Modiolia Marinescu, 1973 † (uncertain)
• Molpalia accepted as Molpadia Cuvier, 1817
• Mongolia Tsuneki, 1972 (uncertain)
• Monoplia Newman, 1845
• Mopalia Gray, 1847
• Morelia A. Richard ex A.P. de Candolle, 1830 [Family: Rubiaceae]
• Morelia Gray, 1842 [Family: Boidae]
• Morellia Robineau-Desvoidy, 1830
• Morgulia Eisig, 1910 (unaccepted)
• Moriola Norman, 1872
• Morionia Jordan, 1910 (uncertain)
• Mormonia Curtis, 1834 (uncertain) [Family: Trichoptera (awaiting allocation)]
• Mormonia Hübner, 1823 [Family: Noctuidae]
• Morobia E. Horak, 1979 accepted as Lepiota (Persoon) S.F. Gray, 1821
• Morokia Janson, 1905
• Morronia Posadas & Ocampo, 2001 (uncertain)
• Mortalia Ryzhkova & Coram, 2016 †
• Mortola Mello-Leitão, 1938
• Mortonia A. Gray, 1852 [Family: Celastraceae]
• Mortonia Desor, 1857 accepted as Mortonella Pomel, 1883 † [Family: Protoscutellidae]
• Mortonia Fritze, 1908 accepted as Aulocrania Uvarov, 1940 [Family: Tettigoniidae]
• Mortonia Gray, 1851 [Family: Echinocyamidae]