Neritina neglecta (W.H. Pease, 1861)
Nerita neritopsoides L.A. Reeve, 1855
Theodoxus neumayri (FOSSIL) (Burgerstein, 1877 †)
Nerita nigerrima J.H. Chemnitz
Clithon nigrispinis R.P. Lesson, 1831
Nerita nigrita (P.F. Röding, 1798)
Theodoxus niloticus L.A. Reeve, 1856
Theodoxus nitens (FOSSIL) Gozhik, 2002 †
Theodoxus nivosus (FOSSIL) (Š. Brusina, 1874 †)
Nerita nodulosa (FOSSIL) A.J. Jukes-Browne, 1877 †
Neritodryas notabilis E. Riech, 1935
Theodoxus novorossicus (FOSSIL) (Sinzov, 1896 †)
Clithon nucleolus (P.M.A. Morelet, 1857)
Theodoxus numidicus (C.A. Récluz, 1841)
Neritina nunoi (FOSSIL) B.M. Landau, F. Da Silva& S.M. Heitz, 2016 †
Clithon obscuratus Unknown Author
Neritina obtusa (W.H. Benson, 1836)
Theodoxus obtusangulaeformis (FOSSIL) Gozhik, 2002 †
Pseudodostia ocalana (FOSSIL) G.J. Vermeij & R. Portell,2013 †
Nerita ocellata E.J. Le Guillou, 1841
Theodoxus octagonus Eichhorst, 2016
Nerita oligopleura (FOSSIL) W.H. Dall & Oschner,1928 †
Clithon olivaceum (C.A. Récluz, 1842)
Nerita olivaria E.J. Le Guillou, 1841
Nerita orbignyana C.A. Récluz, 1841
Nerita ornata (FOSSIL) L.W. Stephenson, 1953 †
Nerita ornata E. Forbes, 1846
Nerita orovillensis (FOSSIL) R.L. Squires & Saul,2005 †
Neritina ortoni (FOSSIL) T.A. Conrad, 1871 †
Nerita oryzarum (C.A. Récluz, 1841)
Clithon oualaniensis (R.P. Lesson, 1831)
Nerita oviformis E. Forbes, 1846
Neritina oweniana (W. Wood, 1828)
Neritina owenii J. Mawe, 1823
Theodoxus oxytropida (FOSSIL) (N.I. Andrusov, 1909 †)