• Unica Gorbach, 1985 † [Family: Pterioida (awaiting allocation)]
• Unica Šnoflák, 1951 (uncertain) [Family: Hymenoptera (awaiting allocation)]
• Unicachichthys Díaz-Cruz, Alvarado-Ortega & Carbot-Chanona, 2016 †
• Unicaecum Stunkard, 1925
• Unicaecum ruszkowskii
• Unicageocoris Malipatil, 2013
• Unicalteutha Wilson, 1944 accepted as Sacodiscus Wilson, 1924
• Unicalteutha ovalis C.B. Wilson, 1944 accepted as Sacodiscus ovalis (C.B. Wilson, 1944)
• Unicantharis Svihla, 1999 accepted as Islamocantharis Wittmer & Magis, 1978
• Unicapella Dingle, 1980 †
• Unicapeltis Maksimova, 1977 †
• Unicapsula Davis, 1924
• Unicapsula marquesi Diebakate, Fall, Faye & Toguebaye, 1999
• Unicapsula maxima Sarkar, 1999
• Unicapsula muscularis Davis, 1924
• Unicapsula pacifica Aseeva & Krasin, 2001
• Unicapsula pflugfelderi Schuberg, Sprague & Reinboth, 1975
• Unicapsula schulmani Aseeva & Krasin, 2001
• Unicapsula seriolae Lester, 1982
• Unicapsulactinomyxon Rangel, Cech, Székely & Santos, 2011
• Unicardiopsidae Vokes, 1967 †
• Unicardiopsis † (uncertain)
• Unicardium d'Orbigny, 1850 †
• Unicardium gibbosum Lycett †
• Unicarinata Pan, 1982 † [Family: Neotaenioglossa (awaiting allocation)]
• Unicarinata Sheng, Li & Sun, 2022 [Family: Ichneumonidae]
• Unicarinatus Cardoso, 1965 † (uncertain)
• Unicarinicola Packer, 2008 accepted as Chilicola Spinola in Gay, 1851
• Unicauda Davis, 1944
• Unicauda andhrae Kalavati & Narasimhamurti, 1981
• Unicauda aplocheili Kalavati, Venkateswara-Rao & Vaidehi, 1992
• Unicauda aristichthydis Zhao & Ma, 1995
• Unicauda armati Gupta & Khera, 1987
• Unicauda basiri Bhatt & Siddiqui, 1964 accepted as Henneguya basiri (Bhatt & Siddiqui, 1964)
• Unicauda bengalensis Chaudhuri & Chakravarty, 1970 accepted as Henneguya bengalensis (Chaudhuri & Chakravarty, 1970)
• Unicauda bicornata Chaudhuri & Chakravarty, 1970 accepted as Henneguya bicornata (Chaudhuri & Chakravarty, 1970)
• Unicauda brachyura (Ward, 1919)
• Unicauda carassii (Fujita, 1924)
• Unicauda caudatus (Gogebashvili, 1966)
• Unicauda chaudhuryi Bajpai & Haldar, 1982 accepted as Henneguya chaudhuryi (Bajpai & Haldar, 1982)
• Unicauda clavicauda (Kudo, 1934)
• Unicauda crassicauda (Kudo, 1934)
• Unicauda limatula (Meglitsch, 1937)
• Unicauda lumae Rahemo, 1976
• Unicauda macrura (Gurley, 1893)
• Unicauda magna Minchew, 1981
• Unicauda monera (Gurley, 1893)
• Unicauda pelteobagrus Ma in Chen & Ma, 1998
• Unicauda plasmodia (Davis, 1922)
• Unicauda retae accepted as Henneguya ritae (Bajpai & Haldar, 1982)
• Unicauda ritae Bajpai & Haldar, 1982 accepted as Henneguya ritae (Bajpai & Haldar, 1982)
• Unicauda spatulata (Fujita, 1924)
• Unicauda strongylura (Gurley, 1893)
• Unicauda wuhanensis Xiao & Chen, 1993
• Unicauda xihuensis Wu & Lij, 1986
• Unicavea d'Orbigny, 1853 † (uncertain)
• Unicavea novaehollandiae d'Orbigny, 1853