• Fordia Gray, 1869 (uncertain) [Family: Trionychidae]
• Fordia W.B. Hemsley in Forbes & W.B. Hemsley, 1886 [Family: Fabaceae]
• Forma † (uncertain)
• Formania W.W. Smith & J.K. Small, 1922 [Family: Asteraceae]
• Formania Whalen & Carter, 1998 † (uncertain) [Family: Sarcomastigota (awaiting allocation)]
• Formiana Druce, 1885
• Formica Linnaeus, 1758
• Formila de Romand, 1846 (uncertain)
• Formio Whitley in McCulloch, 1929 accepted as Parastromateus Bleeker, 1864
• Formosa Ivanova, Alexeeva, Flavier, Wright, Zhukova, Gorshkova, Mikhailov, Nicolau & Christen, 2006
• Fornax Jousseaume, 1888 accepted as Turbo Linnaeus, 1758 [Family: Turbinidae]
• Fornax Laporte, 1835 [Family: Eucnemidae]
• Forsar Gray, 1847 (unaccepted)
• Forsia Malaise, 1931 (uncertain) [Family: Tenthredinidae]
• Forsia Saul, 1988 † [Family: Neogastropoda (awaiting allocation)]
• Fortax Motschoulsky, 1866 accepted as Cyclotrachelus de Chaudoir, 1838
• Fortia Villarreal, Kury & Colmenares, 2022